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MECHANICAL SHOULDER DISORDERS: PERSPECTIVES IN FUNCTIONAL ANATOMY 0-7216-9272-9Copyright © 2004, Elsevier Science (USA). All rights reserved.

No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechan-ical, including photocopying, recording, or any information storage and retrieval system, without permission inwriting from the publisher. Permissions may be sought directly from Elsevier’s Health Sciences RightsDepartment in Philadelphia, PA, USA: phone: (+1) 215 238 7869, fax: (+1) 215 238 2239, e-mail: [email protected]. You may also complete your request on-line via the Elsevier Science homepage(http://www.elsevier.com), by selecting ‘Customer Support’ and then ‘Obtaining Permissions.’

International Standard Book Number 0-7216-9272-9

Acquisitions Editor: Marion WaldmanDevelopmental Editor: Sue BredensteinerPublishing Services Manager: John RogersProject Manager: Mary TurnerDesign Manager: Bill DroneMultimedia Manager: Bruce RobisonCover Illustration: Hans Neuhart

Printed in the United States of America

Last digit is the print number: 9 8 7 6 5 4 3 2 1

Notice

Rehabilitation is an ever-changing field. Standard safety precautions must be followed, but as new researchand clinical experience broaden our knowledge, changes in treatment and drug therapy may become nec-essary or appropriate. Readers are advised to check the most current product information provided by themanufacturer of each drug to be administered to verify the recommended dose, the method and durationof administration, and contraindications. It is the responsibility of the licensed prescriber, relying on expe-rience and knowledge of the patient, to determine dosages and the best treatment for each individualpatient. Neither the publisher nor the author assumes any liability for any injury and/or damage to personsor property arising from this publication.

To our parents,Jean and Carl DeRosa

andMary and David Porterfield

Their words of encouragement, wisdom, and love perpetually resonate through our hearts and souls. We are forever grateful to them for the sacrifices they have made so that all of their children could achieve success.

We love you.

James A. Porterfield, PT, MA, ATCCarl DeRosa, PT, PhD

Good Better Best, Never Let It Rest,Until the Good Is Better and the Better Is Best

PREFACE

Mechanical Shoulder Disorders: Perspectives in FunctionalAnatomy is the result of collaboration by two col-leagues and friends whose professional passion haslong been the study of clinical anatomy and exercisescience. As in our previous Perspectives in FunctionalAnatomy texts, Mechanical Low Back Pain and MechanicalNeck Pain, the intent of this new multimedia packageis to weave these two sciences into a clinically appli-cable model for the evaluation and treatment of thepainful disorders of the shoulder. We also emphasizetraining considerations that will enhance perform-ance for all aspects of living.

The DVD module that accompanies this textbookcontains 2 hours of narrated cadaver dissection,which emphasizes the interdependence of physio-logic structure and function. Commentary regardingclinical application is made throughout each dissec-tion in order to allow both student and clinician toappreciate the musculofascial system as it works todirect forces into and through the skeleton.

The text module coordinates with the DVD. InChapters 2, 3, and 4, the reader will find small cir-cular icons marked “DVD” in the book’s margins.These icons identify content that is enhanced by spe-cific video clips on the DVD. The reader willincrease learning benefit by inserting the DVD andplaying the clips that are listed in the “TextReference Section” while reading the book. Thisinnovative method for learning presents a three-dimensional perspective of the glenohumeral andscapulothoracic regions. Additionally, more than 200superb illustrations are positioned throughout thetext to effectively satisfy the two primary methods of

learning: multisensory (visual) and reading compre-hension. Chapter 5 includes an effective assessmentcomponent with over 40 step-by-step photographs.Chapter 6 focuses on treatment options and includesan exercise section with 48 exercises and 160 photo-graphs that clinicians, exercise physiologists, andpatients will find useful.

Movement is anabolic, and sustaining strength andpainless activities are important to the quality of lifeand a sense of well-being. A true appreciation of ahealthy body can be clearly described only by someonewho has lost the ability to move painlessly and thenthrough hard work and effective guidance hasregained it. Conversely, the process of aging is cata-bolic. The degenerative process, which is compoundedby injury, is what ultimately must be managed.Understanding the close interrelationships betweenexercise (movement) and health maintenance, bothphysical and mental, has been our theme throughoutour textbooks. We remain dedicated to the develop-ment of efficient patient care models that emphasizerehabilitation strategies and direct management ofmusculoskeletal problems. We are especially mindful ofthe need to quantify effective treatment outcomes andthe importance of patient education in ensuring areturn of body function within the medical, therapeu-tic, and economic realities of the current health caremarket. These themes, coupled with an understandingof the three-dimensional anatomy, continue in thisnew product.

James A. PorterfieldCarl DeRosa

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ACKNOWLEDGMENTS

The process of developing and ultimately writing anyscholarly publication provides many exceptionalopportunities to interact with new people and workwith lifelong friends. We have been fortunate to havehad the opportunity to collaborate with numerousindividuals during this unique project that integratesvideo and text. We would especially like to thank thefollowing colleagues and friends for their insight andassistance: Brian Coote, PT, MBA; Debbie Benjamin,PTA; Kurt Lundquist, PT; Richard Monasterio(Monasterio Studios); Dick Fraser (Fraser VideoProductions); Rob Bell, MD; Merrill Abeshaus, MD;our physical therapist colleagues at Rehabilitationand Health Center and DeRosa Physical Therapy atSummit Center, and the faculty at Northern Arizona

University and the Cleveland State UniversityPhysical Therapy Program.

We also would like to extend a very special thanksto Tina Cauller and Sue Bredensteiner. The illustra-tions in this, and in all of our texts, have been drawnby Tina Cauller. Her patience and extraordinary tal-ent significantly add to the quality of our work, andwe thank her for her insight and persistence. SueBredensteiner, the developmental editor for this text,greatly assisted us in organizing and integrating theteaching materials. Her expertise and calm demeanorhelped anchor the project.

“Teach Once, Learn Twice” supports the founda-tion of our growth, and we thank all of our students,past and present, for their interest and collaboration.

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INTRODUCTION

Musculoskeletal disorders are a major health con-cern and remain one of the primary reasons for seek-ing health care. As we approach our 50s and 60s,disorders associated with bones, joints, and musclesare often the cause of worker disability, and there islittle evidence to suggest that disability from muscu-loskeletal disorders is decreasing. While spinal disor-ders are the leading cause of musculoskeletaldisability, they are followed by disorders of the extrem-ities, especially disorders of the upper extremity.

Although low back, neck, and hand and wrist painare commonly involved in work-related injuries, disor-ders of the shoulder are increasingly seen in the workenvironment, particularly when workers are requiredto do repetitive overhead lifting or under conditionswhere static shoulder postures need to be assumed.Work-related disorders associated with the shoulderare often referred to as “occupational cervicobrachialdisorders” and are characterized by symptoms of dif-fuse pain in the paracervical, scapular, and gleno-humeral regions.4 As clinicians, we see that mechanicalshoulder problems are not limited in their presentationto the shoulder girdle, but encompass a fairly extensivearea of the upper quarter. The most common work-related disorders are associated with light industry,assembly line workstations, and office environments.

In this text we will endeavor to present the shouldergirdle complex in the context of its relationship to the

surrounding body area including the neck and arm, aswell as the trunk and lower extremities. As we con-tinue to look for the best ways to treat shoulder disor-ders, it is valuable to integrate the typical local focus ofthe shoulder itself with a more global focus thatincludes its relationship with other areas of the appen-dicular and axial skeleton.

Many work environments are conducive to occupa-tional injuries that result in cervicobrachial disorders.Required tasks often result in static postures of theupper trunk and shoulders and simultaneous rapidmovements of the hands.10,36,42 The disorders thatresult from occupations that require prolonged, staticpostures tend to be related to cumulative microtraumato the musculoskeletal tissues, which can be com-pounded by reduced neuromuscular efficiency. On theopposite end of the injury spectrum, you find workenvironments that require heavy lifting and abrupt,rapid force generation. These occupations have ahigher incidence of macrotraumatic injuries such asrotator cuff tears.

U.S. Bureau of Labor statistics from the past decadereveal an incidence of occupational cervicobrachialdisorders that has increased and now ranks second tolow back and neck pain in frequency.46 Differentoccupations place such unique demands on the muscu-loskeletal system that the prevalence of occupationalcervicobrachial disorders has a broad range, varyingfrom 5% to 28%. In some occupations, such as musi-cians, it may be as high as 75%.20,36

CHAPTER 1

Age

InjuryAdaptive change

Altered loadbearing tolerance

PRINCIPLES OFMECHANICALSHOULDER DISORDERS

1

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The shoulder joint lacks inherent bony stability andtherefore relies heavily on its associated muscles, jointcapsules, and ligaments for stability. This places thesoft tissues of the shoulder, particularly the connectivetissue, at significant risk for injury.29 The dependenceon soft tissue for stability of the shoulder is best under-stood when you recognize that dislocations of theglenohumeral joint account for the largest percentageof dislocations when compared with all the other jointsin the body.27

One of the most common clinical observationsregards the differences seen between body regions ofage-related changes of the specialized connective tis-sues. When considering the age-related changes of thespine, hips, and knees, for example, we are struck bythe degenerative changes associated with the articularcartilage of those joints. In many shoulder disorders,however, the soft tissue of the region is the primarysource of mechanical shoulder pain, for example, inthe tendons and joint capsules, rather than articularcartilage. Certainly arthritis of the glenohumeral jointcan be a major clinical problem, and advancingarthritic conditions of the glenohumeral joint are seenin the older adult population with approximately a20% prevalence.26,48 But we are often struck by thepreponderance of soft tissue disorders related to theshoulder that we see in the clinic.

While industrial injuries have been a major impe-tus for analyzing the biomechanics of the anatomicalregions that are associated with work-related injuries,it is really the sports sciences that have served as thestimulus for the study of shoulder biomechanics.Over the past several years, clinicians and scientistshave begun to combine much of the emerging knowl-edge pertaining to the anatomy and biomechanics ofthe shoulder joints with the burgeoning understand-ing of tissue damage that results from industrialrepetitive strain injuries. This has enabled us to gaina better understanding of the causes of shoulderinjury, the response of the tissue of the shouldercomplex to injury, the strategies that can be used toevaluate the shoulder, and, ultimately, the best waysto surgically and nonsurgically manage shoulderdisorders.

The art and science involved in the evaluation andtreatment of the shoulder depend largely on anunderstanding of the tissue’s response to abnormal orexcessive stress, as well as an application of this knowl-edge to the clinical anatomy of the region. This typeof an approach leads to sound treatment and positiveoutcomes.

In this text we present a carefully illustrated andcomprehensive description of shoulder anatomy in amanner designed to help direct the examinationprocess. Understanding tissue injury and the healingprocess, coupled with the recognition of the role ofthe neuromuscular system of the trunk and shouldercomplex, is essential to the successful treatment. Wealso emphasize the manner in which the strength ofthe trunk and shoulder girdle contributes to loadingpatterns that ultimately reach the connective tissues ofthe shoulder complex. In this chapter we examine thescience of connective tissue as it relates to the shouldersince this tissue is so often compromised in syndromesof the shoulder complex. Additionally, we introduceseveral examples of common connective tissue disor-ders of the shoulder girdle in order to set the stage formore complete consideration of these and othermechanical disorders later in the book.

PURSUIT OF AN ACTIVELIFESTYLE

As a result of many medical advances, the averagelife expectancy increases each decade. Consequentlymany of us are now pursuing sporting and recre-ational activities well into our eighth decade. Amongthe many stimuli for maintaining a healthy and activelifestyle are advances in the understanding of thecauses of osteoporosis and the ways to minimize itsonset, the beneficial effect of activity on the joints andmuscles, the adverse effect of inactivity on the car-diopulmonary system, and the emotional and socialbenefits of exercise. These factors motivate all of us toengage in activities that are enjoyable and also havethe potential to optimize our general health.

Some common activities include weight training,aerobic dancing, golf, swimming, racquet sports suchas tennis and racquetball, and throwing sports. Evenrock climbing is capturing the interest of many.Others make time to learn and play a musical instru-ment. All of these activities can place extraordinarydemands on the muscle and connective tissue of theshoulder complex. Likewise, range-of-motion require-ments and trunk and shoulder muscle recruitment arevery specific and precise for each activity. As a result ofthe increased number of individuals of all ages engag-ing in such varied activities, shoulder injuries nowappear with greater frequency.

Rotator cuff tendon lesions provide a good exampleof the magnitude of shoulder disorders in the general

2 PRINCIPLES OF MECHANICAL SHOULDER DISORDERS

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population. The variability of rotator cuff lesionsmakes it extremely difficult to assess the incidence ofthese tears precisely because age plays such a signifi-cant factor in the pathogenesis of this injury. As aresult of the wide variation in signs and symptoms,and lack of understanding with regard to the differ-ences between the normal aging process and degener-ation, incidence rates have been placed as low as 5%and as high as 90%.55 Especially in the older adultpopulation, incidence rates for cuff tears may be ashigh as 90%.14 As is the case with many other areas ofthe body, it is difficult to determine what is normal,expected aging and degeneration of tissues and whatis a true pathological lesion.

Rotator cuff tears vary from being partial to fullthickness (see Chapter 3). These injuries may presentas painful entities or may not be painful at all; cuff dis-orders may result in significant functional deficit orleave no functional limitation.38

Thus, despite our continued advances in the studyof sport science and repetitive strain injuries in theworkplace, the simple fact remains that the primarycause of rotator cuff degeneration is age. Age resultsin a decrease in tendon elasticity and tensile strength,and these changes occur in active, as well as sedentary,individuals. And this emphasizes an important clinicalconcept: tendon lesions have a limited capacity to heal,though symptoms may decrease. Therefore symptomreduction is an unreliable way to determine tendonintegrity.

Regardless of the presence or absence of symptomsand signs that might indicate cuff tears, loss of tendonintegrity compromises the stability of the shoulder.Furthermore, such soft tissue injury associated withthe shoulder joints results in altered joint kinematics,which may result in additional degenerative changesto surrounding tissues of the shoulder complex.

Key Role of Tissue MobilizationVersus Immobilization

The advances in understanding the response ofconnective tissue to injury, age, and adaptive changehave occurred simultaneously with an enhancedunderstanding of the clinical anatomy of the shouldercomplex and the contribution by the various compo-nents of the complex to its remarkable mobility. Weknow that immobilization is tolerated very poorlybecause motions of the shoulder girdle encompassseveral articulations and interfaces. In fact, immobi-

lization of the shoulder can lead to irreversiblechanges and a permanent loss of function.33,45,47,50

The deleterious effect of prolonged immobilizationand the pronounced effect of disuse on the connectivetissues result in structural changes to the tissues. Forexample, as a result of immobilization, the fibers ofligaments become increasingly disorganized and losetheir parallel structure. Ligaments lose their structuralrigidity, and as a result, less energy is needed to deformthem.1,15 Fibrous tissue with fatty inlays begin toinvade the connective tissue and then adhere to thearticular cartilage surface in the absence of jointmotion.2

The properties of all the key connective tissue struc-tures, such as synovial membranes, joint capsules, lig-aments, tendons, insertional sites of tendons andligaments, and the bones, are all adversely affectedwith immobilization and inactivity. The result is thatthese tissues can no longer attenuate compressive,tensile, or shear loads.7

Concurrent with changes in the connective tissues,the muscle tissue loses its volume and its normal func-tion is also altered. In as little as 2 weeks, the mass ofmuscle begins to decrease because of a loss of myo-fibrils, and the oxidative enzymes needed for mito-chondrial activity begin to diminish.13 The strength(torque-generating ability of the muscle) and theoxidative capacity (necessary for muscle endurance) ofthe muscle therefore are decreased. The relative mus-cle atrophy seen so often in the sedentary individualsis a major concern. The loss of lean muscle mass cou-pled with skeletal changes that occur during agingrender our bodies less able to deflect the barrage offorces that reach the articulations during daily activi-ties of living, work, and sport.

In Chapter 3 we describe the anatomy and mechan-ics of the shoulder girdle muscles in detail. In additionto the role of these muscles in the movement of thevarious bony levers, we also point out the mechanicallinkages each muscle has with connective tissue struc-tures such as the joint capsules, ligaments, and fascialnetworks. In order to better understand how musclescontribute to the stability of an inherently unstableregion like the shoulder girdle, it is necessary tobroaden our view of the role muscles play over thearticulations. The intimate relationship between mus-cles and specialized connective tissues is illustrated bythe linkages seen between the rotator cuff muscles andjoint capsule: the various muscles attached to andlying within the infraspinatus fascia, the convergenceof numerous powerful muscles at the inferior border

PRINCIPLES OF MECHANICAL SHOULDER DISORDERS 3

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of the scapula, and the relationship of the abdominalfascia to the muscles of the anterior chest wall.

In these and other instances you can compare themuscle–connective tissue dynamics to the way inwhich a tent is stabilized. The central pole of the tentequates to the pushing effect the muscles, encasedwithin the fascial envelopes, have as a result of thebroadening effect of their contraction. External to thissame fascial envelope are the pulls of various muscles,which act like the guy wires of a tent in securing andtightening the structure. Stability of the tent isachieved when the central post is pushing with appro-priate force, and the guy wires are pulling in a mannerthat maintains tension within the tent walls. An excel-lent example, detailed in Chapter 3, involves the roleof the infraspinatus fascia and the muscles encasedwithin (the center pole of the tent) and attached to theexternal aspect (the guy wires pulling on the tent).

As a result of our understanding of the importancethe musculature plays, current rehabilitation conceptsassociated with management of mechanical shoulderdisorders feature earlier initiation of motion exercisesfor all of the key components of the shoulder complexand strength training of the glenohumeral, scapu-lothoracic, and trunk muscles (see Chapters 3 and 6).The intent of a more aggressive but specific approachto continued mobilization is to minimize the atrophyof the glenohumeral musculature. This is importantbecause the glenohumeral joint is so highly dependenton neuromuscular control of the humeral head withinthe glenoid, and full shoulder motion requires the syn-chrony of scapula motion on the thorax. Earlier reha-bilitation is now possible as a result of advances insurgical techniques and arthroscopic procedures thatminimize the morbidity of the surrounding tissues.39

Influence of Body Type onMusculoskeletal Syndromes

Similar to most regions of the appendicular skele-ton, the joints and soft tissues are subject to varyingloads and diverse combinations of forces. Themechanical loads that reach the various tissues of theshoulder are compression, tension, and shear. Theseforces can reach different tissues of the shoulder inmany different ways. An analysis of a posteriorlydirected shear force at the glenohumeral joint is agood example (Figure 1-1). A posterior shear betweenthe head of the humerus and the glenoid fossa can beimparted to the joint via the alignment of the two

bones during a push-up. A posterior shear force alsocan occur as a result of contraction of the posteriorcuff muscles. In a completely different scenario, a tightanterior glenohumeral joint capsule may generate aposterior shear of the humerus on the glenoid whenthe humerus is brought backward toward hyperexten-sion. And in yet another example, an examiner mayapply a posterior shear force through the humeruswith a simple anterior-to-posterior force as long as thisforce is applied in the plane of the scapula. Note ineach of these examples that the forces of compressionand tension are simultaneously reaching different tis-sues, and it is essential that these forces be modified bythe connective tissues as well.

The response of the tissues to forces of compres-sion, tension, and shear is dependent on many factors,but one that needs to be considered in the evaluationof the patient is the body type. This is especially truein the examination of a patient with shoulder pain (seeChapter 5). Forces applied to the ectomorphic, highlyinflexible individual result in a much different tissueresponse than forces applied to a mesomorphic, mus-cular individual or an endomorphic, highly flexibleindividual. Recognition of the body type often directsthe clinician toward a different hierarchy of treat-ment. For example, it may be more appropriate toplace additional emphasis on strengthening in an indi-vidual with a seemingly lax connective tissue matrixthan to focus on stretching techniques, while anemphasis on motion and flexibility may be a betterapproach for the individual with a more rigid connec-tive tissue matrix. Consideration of body type is there-fore essential in the evaluation and treatment of mostshoulder disorders.

When we analyze the broad spectrum of shoulderdisorders seen in the clinic, the end result of manymechanical shoulder disorders can be distilled intospecific biomechanical conditions: compression prob-lems especially within the coracoacromial arch, tensileoverload especially within the cuff tendons, and gleno-humeral joint instability that results in excessive trans-lation of the humeral head on the glenoid as a resultof the inability to attenuate shear forces. Two exam-ples of these biomechanical conditions are increasedcompression of the soft tissues residing in thesuprahumeral space, which might occur with elevationof the humeral head, and humeral head subluxation,which might result from a redundant glenohumeraljoint capsule. In these two very different clinicalexamples, a change in the connective tissues hasresulted in two distinctly different clinical conditions.


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Infraspinatus

Subscapularis

Compression

OBLIGATE POSTERIOR TRANSLATION

Figure 1-1. Posterior shear force is applied to the glenohumeral joint. A, From a push-up as aresult of weight bearing. B, Through contraction of the posterior cuff muscles. C, As the result ofa tight anterior glenohumeral joint capsule. D, As a result of the examiner applying posterior shearloads via the lever of the humerus. (B and C from Rockwood CA Jr, Matsen FA III, Wirth MA, et al: The shoulder, ed 2, Philadelphia, 1998, WB Saunders.)

A

B

C

D

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The compression of the soft tissue that resides in thesuprahumeral space might be due to the tightness ofthe posterior aspect of the glenohumeral joint capsule,which forces the head anteriorly during humeral ele-vation (see Chapter 4). Conversely, tightness of theanterior capsule pushes the humeral head posteriorly,and, more critically, tightness of the capsule in thisanterior region does not allow the glenohumeral jointto reach full external rotation. Without full externalrotation, the greater tuberosity cannot be clearedunder the acromion during glenohumeral elevation.

Both syndromes result in increased compressiveload to the subacromial tissues. Paradoxically, laxity ofthe glenohumeral joint capsule also may result inincreased compressive loads to the subacromial tissuesalbeit for different reasons. The laxity of the gleno-humeral joint capsule results in aberrational move-ment of the humeral head on the glenoid especiallyin the presence of a weak or fatigued rotator cuff. Thesubacromial tissues are again compromised viacompression under the coracoacromial arch.

Again, body type is an important considerationbecause you may be able to estimate the magnitude ofthe abnormal or excessive loading patterns that reachthe shoulder due to the activities in which an individ-ual is engaged. For example, different swimmingstrokes have dissimilar requirements of the variousshoulder tissues. Throwers have very specific biome-chanical requirements for attenuating stresses. Again,the body type and the particular activity involved mayinfluence the treatment priority hierarchy. A youngfemale swimmer with a lax connective tissue matrix isa strong candidate for glenohumeral instability prob-lems, which lead to secondary changes in the rotatorcuff musculature. The glenohumeral joint of the base-ball pitcher with a lax connective tissue matrix receivesextraordinary shear loads between the humeral headand the glenoid during throwing, and the connectivetissue framework may not reasonably contribute tostabilization of the joint.

On the other hand, the middle-age golfer who hasa more rigid connective tissue matrix may have lessglenohumeral and hip joint motion as a result ofadaptive changes in the joint capsules. In order tocarry out the golf swing, this golfer must compensatefor lack of motion at these two proximal appendicularjoints with excessive torsion of the lumbar spine.

Therefore it becomes important to closely examinethe overall joint laxity of patients who present withmechanical shoulder problems. This is easily done byquickly screening the other joints of the body, such as

the elbow or first metacarpal-phalangeal joint, formultiplanar mobility and the resistance imparted tothe examiner’s hands with endrange positions. Oftenthe assessment of the turgor and elasticity of the skincan also provide the examiner with clues to the expectedcontributions of specialized connective tissues associatedwith the shoulder joints.

Can glenohumeral joint laxity be acquired throughactivity? Based on our knowledge of the response ofconnective tissue to different stresses (discussed later inthis chapter), it is logical that excessive forces appliedcontinuously and for extended periods of time may havethe ability to alter the connective tissue matrix. Youshould always suspect instability of the glenohumeraljoint in athletes or workers who engage in repetitiveoverhead activities that simulate the movementsrequired in swimming, throwing, and racquet sports.Indeed, this possibility presents a dilemma: the joint cap-sule needs sufficient laxity in order to allow us to engagein the activity, yet the capsule must have enough stiffnessto stabilize the joint. Perhaps no other joint in the bodydepends on such a fine line delineating the requirementsfor mobility versus the requirements for stability.

CONNECTIVE TISSUE WITHSPECIAL REFERENCE TO THE SHOULDER COMPLEX

There are a variety of different types of tissue in thehuman body, including epithelial, connective, blood,muscle, adipose, and nerve. All are considered tissuesbecause they consist of cooperating cells that areformed into coherent associations, which are then sur-rounded by fibrous and amorphous intercellular sub-stances. Each of the tissues of the body is representedin the shoulder complex, but this section will focus onconnective tissue. The key components of the shoul-der, including the rotator cuff tendons, biceps tendon,glenohumeral ligaments, glenohumeral joint capsules,bursal tissue, acromioclavicular capsule, and support-ing ligaments, are prime examples of the connectivetissues that are associated with mechanical disorders ofthe shoulder girdle.

Connective tissue is ubiquitous within the shouldercomplex (Table 1-1). The whole family of connectivetissue can be subdivided into connective tissue properand the subclasses of specialized connective tissue(Figure 1-2). Even though there is a marked physicaldifference between connective tissue proper and spe-cialized connective tissue, both tissues are considered


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to reside within the same family because of the simi-larity among the building blocks, namely cells, inter-cellular matrix, and fibers.

Connective tissue proper can be subdivided intoloose connective tissue and dense connective tissue.Loose connective tissue forms highly irregular matri-ces that help to protect and hold structures such as thevessels and nerves in place, or serve as tissue interfacesas seen in the case of bursal tissue. The axilla featuresan extensive array of loose connective tissue that alsoincorporates fat tissue into its weblike structure, pro-viding additional support and cushion for the brachialplexus and the blood vessels in the axilla.

Dense connective tissue structures can be subdividedinto regular and irregular tissue, with the clinically key

subdivision being the dense regular type. Examples ofdense regular tissue in the shoulder include the rotatorcuff tendons, biceps tendons, the various ligaments ofthe glenohumeral joint, acromioclavicular joint, andsternoclavicular joint, and the joint capsules. Eventhough dense connective tissue has an abundant fiberframework, water still constitutes approximately 80%of its total makeup, followed by fibers (15% to 20%),and glycosaminoglycans (2%).23 While we discuss thebinding of water to these molecular elements later, ingeneral, the greater the concentration of proteoglycanswithin the individual types of connective tissue, thegreater the percentage of water.

Specialized connective tissue includes tissue withspecific structures that allow for singular, individual-


Table 1-1. Connective Tissues of the Shoulder Complex

Bone Articular Cartilage Ligaments Joint Capsules Joint StructuresHumerus Humeral head Glenohumeral Glenohumeral Glenoid labrumScapula Glenoid fossa Coracohumeral Acromioclavicular AC discClavicle Medial acromion Coracoacromial Sternoclavicular SC discSternum Lateral clavicle Transverse humeral Cervical apophyseal BursaeRibs Medial clavicle Coracoclavicular Synovial liningCervical vertebrae Sternum Costoclavicular Mechanoreceptors

Cervical facets Transverse scapular

AC, Acromioclavicular; SC, sternoclavicular.

Connective tissue proper

CONNECTIVE TISSUE

Loose Dense

Regular Irregular

TendonLigament

AponeurosesJoint capsules

Specialized connective tissue

Unique properties Unique structure

AdiposeElasticMucous

Hematopoietic

BoneCartilage

Figure 1-2. Schematic diagram of the principal types of connective tissues. (From Porterfield JA,DeRosa C: Mechanical low back pain: perspectives in functional anatomy, ed 2, Philadelphia, 1998, WBSaunders.)

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ized physical properties. Two examples are bone andarticular cartilage. The cellular and intercellularmakeup of these two specialized connective tissues, aswell as their physiology, are unique when comparedwith other forms of connective tissue. Despite suchspecialization, the general makeup remains similar tothe general organizational scheme of tissues withinthe connective tissue proper, namely cells and anintercellular matrix composed of fibers and groundsubstance.

The distinguishing characteristics of the connectivetissue are the result of distinct types of cells locatedwithin the specific tissues. These cells in turn synthe-size the biochemical composition of the intercellularmatrix. Although connective tissue cells are derivedfrom the common mesenchyme precursor cell, thatmesenchyme cell ultimately is differentiated into sev-eral cell types including the fibroblast, chondroblast,and osteoblast. These cells then become responsiblefor synthesizing the precursors of the fiber framework,as well as the molecules that form the matrix for thefibers and cells.

The capacity of connective tissue to resist differentstresses such as compression, tension, and shear is dueto the properties of its fibers and ground substanceand the interaction between the two. For example, theresiliency and deformability of the articular cartilageof the humeral head and glenoid fossa, the structuralrigidity of the scapula, clavicle, and humerus, and theability of the glenohumeral ligaments and joint cap-sule to yield are all dependent on the specific types,proportions, and aggregations of glycosaminoglycansand proteins that form the ground substance of theirspecific connective tissue and the type, quantity, link-ages, and orientation of intercellular fibers locatedwithin the matrix. In order to better understand therole of the matrix, we will look more closely at thekey intercellular components: collagen fibers andglycosaminoglycans.

Intercellular Componentsof Connective Tissue

There are three basic types of fiber seen in thevarious connective tissues: collagen, which consti-tutes the majority of connective tissue fibers, elasticfiber, and reticulin fiber. Collagen, being the mostabundant, is further classified into subtypes.18

Tendons and ligaments—the tissues most oftenaffected with shoulder disorders—are primarily com-

posed of Type I collagen. Collagen typically makesup approximately 80% of the dry weight of connec-tive tissue and is the only component of tendons, lig-aments, or joint capsules resistant to tensile stresses.Such resistance to tensile stresses is an extremelyimportant consideration for the shoulder since tensilestresses to the joint capsule and ligaments from repet-itive motions or forced movement and eccentricloading of the rotator cuff tendons are among themore common etiologies for several of the mechani-cal disorders of the shoulder.3

The fundamental building block for collagen, whichis synthesized by the fibroblast, is the tropocollagenmolecule. A collagen precursor molecule is actuallysynthesized within the fibroblast cell and then secretedinto the intercellular medium as tropocollagen.Tropocollagen consists of three polypeptide chainsthat are wound around one another in a helix andheld together via cross-links through hydrogen bond-ing (Figure 1-3). As the building block of a tropocolla-gen molecule is added to other tropocollagenmolecules end-to-end (in series) or side-by-side (in par-allel), the collagen fiber begins to assume its shape (i.e.,it begins to form the ligament, tendon, capsule, orother identifiable structure). Its orientation and bond-ing is directed, in part, by the stresses to which the cellsand tissues are subjected. Tropocollagen molecules areheld together in the formation of collagen fibers bystrong covalent bonds. Because tropocollagen consistsof polypeptide chains, collagen is essentially organizedstrands of protein molecules.

The second important class of chemicals that makeup connective tissue is the glycosaminoglycans(GAGs), which also are produced by the fibroblasts.GAGs are chains of polysaccharides with repeatingunits: each unit is composed of a sugar molecule anda sugar with amine molecule (Figure 1-4). The num-ber of repeating units (sugar amine and sugar) ulti-mately determines the length of the GAGs. Eventhough GAGs do not constitute as large a propor-tion of the dry weight of connective tissue as the col-lagen fiber, their importance lies in their affinity forwater.

The final molecule to consider in a study of con-nective tissue is the proteoglycan. These large mole-cules consist of many GAGs linked to proteins. SeveralGAGs become linked to a core protein, which thenforms a proteoglycan unit. In turn, a group of proteo-glycan units can be linked together via hyaluronic acidto form a proteoglycan aggregate. The linkage of pro-teoglycan units through hyaluronic acid, for example,


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provides the basis on which articular cartilage beginsto assume its mechanical properties.

It is important to appreciate the physical structureof proteoglycan units and aggregates. The aggregatesare twisted in various patterns resembling a fine mesh.The physical structure of the mesh, in combinationwith the electrical binding affinity of the proteoglycanto water, forms a structure that attracts and absorbswater and keeps it physically attached to the proteo-glycan aggregates (Figure 1-5). This gives connectivetissues with large concentrations of proteoglycanaggregates larger water content, such as occurs inarticular cartilage, whereas a connective tissue withsmaller proteoglycan content, such as a tendon, doesnot have the same quantity of water. Since differentproteoglycans have different electrical charges, someare more adept at binding water than others. The lossof water from the various connective tissues as a result


1.5 nm

Tropocollagen

280 nm

Myofibril

Figure 1-3. In the structure of collagen, the fundamental unit is tropocollagen, which consists ofthree separate polypeptide chains wound together in a helix.

Sugaramine Sugar

Repeating unitof glycosaminoglycan

Sugaramine

Figure 1-4. Repeating units of glycosaminoglycansappear as long chains of polysaccharides formed by arepeated sequence of a sugar molecule and a sugar withamine molecule.

Hyaluronicacid

Core protein

Keratinsulfate

Chondroitinsulfate

Figure 1-5. The convoluted shape of the proteoglycanaggregate, coupled with its affinity to water as a result ofits electrical charge, makes it strongly attractive to thewater molecule.

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of aging is due in part to two different factors associ-ated with proteoglycans: a decrease in the absolutenumber of proteoglycans, as well as a changing propor-tion of the individual types of proteoglycans. As weage, different proteoglycans are no longer synthesized,which results in changes in number and proportionwithin the tissue.

While all of the features of the individual compo-nents of connective tissue contribute to its strength,one of the major factors is the ability of collagen andproteoglycan to bond together. This bonding givesconnective tissue its ability to attenuate the variousstresses it is subjected to, including compression,tension, and shear.

Basic Biomechanics of the Connective Tissues

The differences among the several types of connec-tive tissue allow each to respond to stress in a differentway. For example, the way in which bone responds tocompressive loads is dissimilar to how tendonsrespond. Likewise, a tensile stress applied to ligamentswill be modified in a different way than a tensile stressapplied to articular cartilage.

The following discussion has significant clinicalimplications because there is often great attention toflexibility and range-of-motion exercises for manyproblems associated with the upper quarter. For exam-ple, a tight glenohumeral joint capsule that limitsexternal rotation is going to have a significant impacton an individual’s ability to raise his arm completelyoverhead. Quite simply, full elevation of the arm isdependent on achieving full external rotation of theglenohumeral joint. This is even more problematic inthe glenohumeral joint because the rotator cuff ten-dons are intimately blended with the capsular tissue,so in essence the joint is a composite of ligamentous(glenohumeral ligaments), capsular (glenohumeraljoint capsule), and tendinous (rotator cuff tendons) tis-sue (see Chapter 4). This begs the question, “Can apatient stretch a contracted, tight joint capsule in thisinstance?”

Much of the clinician’s ability to actually modifyconnective tissue is dependent on several factors.These factors include the type of tissue, age of thetissue, thickness of the tissue, time since injury of thetissue, and inflammatory versus scarred condition ofthe tissue. You must recognize these factors because itis their various combinations that ultimately deter-

mine whether or not the connective tissue structurescan, in fact, be stretched to a new resting position.Obviously, there are fundamental properties of con-nective tissues that ultimately influence and directtreatment approaches. Understanding the basic bio-mechanics involved will help you consider their impli-cations in the evaluation and treatment process.

Stress and Strain on ConnectiveTissue

Clinical treatment protocols often include stretch-ing maneuvers or techniques that are designed to elon-gate the nonosseous connective tissues. By definition,the force, which the clinician directs toward the tissue,is referred to as a stress, and the magnitude of thedeformation that occurs as a result of the elongationforce is known as the strain. Strain is thus measured asa length of change (in millimeters or inches) or as apercentage change from the initial length of the tissue.A tissue can deform if it is squeezed together (a com-pression strain) or if it is elongated (a tension strain).

The normal resting state of the collagen fiber issuch that the individual collagen fibers have a wavyappearance (Figure 1-6). This characteristic of the col-lagen fiber is referred to as its crimp.17 When a stress isapplied to the collagen fiber in a direction parallel tothe fiber orientation, the undulations are first takenout of the fiber (crimp is removed) and slight elonga-


Fiber Fibril

Microfibril

Figure 1-6. The wavy shape of the collagen fiber, theso-called “crimp” of the fiber, allows it to be slightlylengthened when an elongation force is applied.

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tion occurs. Therefore the general “give” or elasticspring of the connective tissue that occurs as the jointis moved passively toward the endranges is responsiblefor this removal of crimp. Very little force is requiredby the examiner to remove the undulations from thecollagen fiber because no chemical or electrical bondshave to be cleaved.

When the undulations of the resting collagenfiber are removed and the elongation force contin-ues to be applied, the collagen fiber resists the forcebecause of the bonding of the individual elements,specifically the linkage between the tropocollagenand the collagen fiber strands. As compared with themagnitude of force needed to remove crimp, themagnitude of force to induce strain in the collagenfiber without crimp is much greater because at thismoment, the force is attempting to overcome thebonding of the connective tissue elements. Becausethe ligaments and joint capsules consist primarily ofcollagen fibers, the stress-strain curve for an individ-ual collagen fiber is very similar to the stress-straincurve of the ligaments albeit with a few differences(Figure 1-7).34,35

As we just noted, the stress first removes the crimpfrom the collagen fiber and then greater energy isrequired to elongate the fiber because chemical and

electrical bonds must be broken. When these bondsare broken, the fiber is less resistant to opposing theforce and the stress results in a greater strain until thefiber fails completely. Capsules and ligaments arelarge, thick sheets of connective tissue, so in additionto the effect of the stress at the individual collagenfiber level, the stress will also cause the reorganizationof the fibers as they attempt to align themselves in thedirection of the stress. Once again, such reorganiza-tion would require that bonds be broken and thusenergy is required.

You can also visualize that the reorganization offibers that results from the elongation force squeezesthe fibers together and water is expressed out from themolecule—again, a breaking of the chemical bondsthat hold water (Figure 1-8). The breaking of chemi-cal bonds that results in strain is a key point, becausevery often clinicians think of strain in terms of rupture


0

Str

ess

1 2 3Strain (% elongation)

4 5 6 7

Clinical range

Crimp

Macrofailure

Figure 1-7. The stress-strain curve for ligaments is verysimilar to the stress-strain curve of collagen. First thestress removes the crimp from the collagen fiber, thenincreased energy is required to elongate the fiber becausechemical and electrical bonds must be broken. Whenthese bonds are broken, the fiber loses resistance andadditional stress results in greater strain until the fiberfails completely. (From Porterfield JA, DeRosa C:Mechanical low back pain: perspectives in functional anatomy, ed2, Philadelphia, 1998, WB Saunders.)

H2O

Coreprotein

Figure 1-8. The collagen framework of large connec-tive tissue structures such as joint capsules and ligamentsis made up of closely approximated individual fibers.When elongation stresses are applied, the response is tosqueeze out water.

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of the collagen molecule itself, which is not quiteaccurate.25

One can see then that once the bonds betweentropocollagen and the filaments of the collagen havebeen broken, it takes only minimal force (appliedstress) to further disrupt the collagen matrix. This ispart of the rationale for manipulation under anesthe-sia for the glenohumeral joint capsule that is rigor-ously adhered and tight. The manipulative thrust inthis case is designed to break the chemical and electri-cal bonds in order to decrease the resistance tomotion. Once those bonds are broken, the clinicianmust work with the tissue continuously and prudentlyin order to be sure that the healing process results inan elongated, more elastic scar that allows the maxi-mal amount of glenohumeral motion to be achieved.This is achieved only if the tropocollagen frameworkbegins to align itself along the natural lines of elonga-tion stress.

In summary, an applied elongation stress has thepotential to initiate a cascade of events. These includeremoval of crimp, breaking of bonds to separatetropocollagen molecules from collagen filaments, reor-ganization of the collagen fiber orientation, and theexpression of water from the framework, nearly all asa result of breaking chemical and electrical bonds.

Within this cascade, approximately how much elon-gation can occur before bonds actually become bro-ken? This is a difficult question because currentresearch has been done with very specific butmarkedly different tissue such as ligament and tendon.Therefore determining a universal failing point is verydifficult because such a failing point is dependent onfactors including the rate at which the stress is appliedand the cross-sectional area of the tissue. Generallystresses applied that result in a strain increasing tissuelength by 1.5% to 3% are considered to be within thephysiological limits of the tissue. Some mechanicalfailure is assumed to occur once the strain begins tosurpass the 3% increase.44,52

Biomechanics of Connective TissueUnder Repetitive Loading

While a discussion focused on the application of asingle stress that might exert strain above and beyondthe physiological loading capacity of the connectivetissue might be applicable to a one-time impact injurysuch as forced external rotation resulting in dislocationof the glenohumeral joint, it is also important to con-sider the effects of repetitive loading on connective

tissue. Many mechanical shoulder disorders are theresult of such cumulative stresses. This was alludedto previously when we reviewed the increased rateof shoulder disorders resulting from workplace move-ment requirements. It is also obvious that the repeti-tive motions used by the swimmer, thrower, andmusician are more akin to overload of the connectivetissues via submaximal cumulative stresses than single-impact loading conditions.

The structural integrity and function of the shoul-der complex depends largely on the ability of the mus-culoskeletal system to respond to repetitive loading.Because of the high degree of mobility found withinnearly all components of the shoulder complex (e.g.,the glenohumeral, acromioclavicular, and sternocla-vicular joints and the scapulothoracic articulation)repetitive loading takes on great importance and canresult in negative or positive consequences. It is notjust the injury process that warrants the study of theinfluence of repetitive motion on injured tissue.Controlled loads can also accelerate the repair of damagedconnective tissues, just as uncontrolled loading has thepotential to inhibit further healing.7

In order to maintain optimal health of connectivetissue, repetitive loading must be of a particular inten-sity, frequency, and range. If repetitive loading fallsbelow or exceeds the optimal range, the various cellsof the connective tissues begin to alter the intercellu-lar framework.19,49 Cells of the different connectivetissues (fibroblast, chondroblast, osteoblast) interpretthe signals related to the patterns of tissue loading andrespond by redirecting the organization of the inter-cellular matrix. Unfortunately, the precise optimalphysiological dose necessary to stimulate the variousconnective tissues is largely unknown and is difficult topredict because the dosage variability is influenced bymultiple diverse factors such as age, endocrine factors,genetics, and environmental stress.

In previous texts we have used a bell curve model toillustrate the response of tissues to stress.40,41 Whenthe stress applied to tissues exceeds the physiologicalcapacity of the tissues, tissue damage occurs. Likewise,when normal physiological loading of the tissue isdecreased or absent, the tissue weakens. Several fac-tors can influence this load bearing tolerance of thetissue, namely age, injury, and adaptive changes ofthe tissues themselves (Figure 1-9).

This concept of a bell curve can also be used toillustrate the principle of repetitive loading of the con-nective tissue of the shoulder, which must accommo-date the many repetitive cycles inherent in sport and


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work activity (Figure 1-10). When the loading cyclesfall below the level necessary to stimulate the connec-tive tissue cells, synthesis of intercellular matrix fallsbehind the process of tissue degradation and the tis-sue becomes substantially weakened. Conversely,increased rates of loading stimulate an adaptive cellresponse, which increases synthesis of intracellular

matrix. If the loading intensity increases beyond thecapacity of the cellular adaptive response, however,the tissue becomes damaged from overload.

The rehabilitation process is framed around thisconcept of cellular response to stimulus. What is theoptimal dose of exercise? What is the optimal dose ofstretch? What is the optimal dose of rest? As simple asthese questions may seem, they are the essence ofrehabilitation program design. The intent of treat-ments to the shoulder is focused on optimization ofthe healing environment in order to restore anatomi-cal relationships between the injured and noninjuredtissues, maintain the normal function of the nonin-jured tissues, and prevent the patient from placingexcessive stress and strain on the injured tissues whiletissue strengthening treatment strategies are imple-mented (see Chapter 6). Training programs should bedesigned to progressively increase the frequency ofexercise in order to take advantage of the cellularadaptive response. Changes can be expected to occurin ligament, bone, tendon, and cartilage as a result ofthe repetitive cyclic stress of exercise.5,16 Repetitiveloads that are applied to the tissues result in realign-ment of the intercellular matrix, and the repetitivestresses are transmitted to the cells of the tissue, result-ing in further synthesis and alignment of the mole-cules comprising the matrix.28,30 This is especiallyvaluable to consider in cases of rotator cuff or gleno-humeral joint capsule repair. Tensile loading of therepaired connective tissue results in the cells and col-lagen framework aligning parallel to the line of theapplied tensile stresses, whereas the lack of appliedtension leaves a more disorganized cellular and matrixenvironment.5,6 Controlled loading of the repairedconnective tissues also influences the rate of healing.Repaired tendons that are treated with controlledmobilization typically show significantly greaterstrength at nearly every point along the healing timeframe than tendons that are left immobilized.21,54

Failure of Connective Tissueto Adapt to Repetitive Stressin the Rotator Cuff Tendon

The rotator cuff tendons provide a good example ofthe continuum of tissue damage, beginning withinflammation, progressing to degradation, and endingin fiber disruption. In many sports conditioning pro-grams, the rotator cuff muscles must work at a highlevel both concentrically and eccentrically to controlglenohumeral motion, as well as maintain the head of


Age

InjuryAdaptive change

Altered loadbearing tolerance

Figure 1-9. The optimal loading zone of tissues of thebody can be changed as a result of age, injury, or adap-tive change to the tissue.

Load bearingtolerance

DamageWeakness

Below rate Above rate

LOADING CYCLES OFCONNECTIVE TISSUE

Figure 1-10. The concept of the optimal repetitiveloading zone is important to the understanding of thepotential for mechanical breakdown of the connectivetissues. When the loading cycles fall below the rate nec-essary to maintain connective tissue integrity, synthesis ofintercellular matrix falls behind the process of tissuedegradation and the tissue becomes substantially weak-ened. Increased rates of loading first result in an adaptivecell response, which increases synthesis of intracellularmatrix. If the loading intensity increases beyond thecapacity of the cellular adaptive response, the tissuebecomes damaged from the overload.

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the humerus in the center of the glenoid fossa.Inappropriate training programs can potentiate thecascade of tissue injury events.19 Training programsfor many sports, such as swimming, throwing, tennis,and weightlifting, include so many repetitive loadingcycles that the adaptive response of the fibroblastswithin the cuff tendons may not meet the demandsthat are being imposed by the training program.

As might be expected, the initial changes that occurare usually at a microscopic level. The tissue may lookmacroscopically intact, but as discussed earlier, signifi-cant disruption and damage to the molecular frame-work of the cuff tendon matrix results in a markedlyweakened tissue. This abnormal rearrangement of themolecular matrix results in a tendon that now can bemore easily damaged by low-level loads. It is impor-tant to note that macromolecular reorientation canweaken the tissue. And this weakened tendon mayrupture when subjected to an exceptionally high force,for example, a strong eccentric contraction when try-ing to throw at a maximum velocity, or attempting tolift a heavy object with a rapid, jerking motion.11

In contrast, decreased loading of the rotator cufftendons is also damaging to the environment aroundthe tendons. The rotator cuff tendons, just like othertendons, are subjected to tensile stresses through theconcentric and eccentric contractions of the cuff mus-cles. When tissues that normally resist tensile stressesare not subject to this stimulus, the degradation of theintercellular matrix begins to exceed the synthesis ofnew matrix. Furthermore, as new matrix is synthe-sized, it is not oriented along lines of stress and is aninherently weaker tissue. The cellular changes thatoccur include a decrease in the amount and differentproportions of GAGs, an obligatory loss of water as aresult of GAG loss, and random orientation of thecollagen fibrils.9,56

DISORDERS OF THE SHOULDERGIRDLE COMPLEX

In the preceding sections we attempted to provide abasic understanding of the mechanics of the special-ized connective tissues at both the cellular and macro-scopic levels. It is important to remember from theprevious discussion that balance must be maintainedbetween physiological stresses that enhance the tissue’shealth and physiological stresses that potentially breakit down. Most of the mechanical disorders of theshoulder discussed in this text are largely the result of

degenerative changes to or injury mechanisms in con-nective tissue structures. Additionally, nonsurgicalmanagement of such connective tissue injuries largelyfocuses on the education of the patient, emphasizingnew biomechanical limits and exercise to enhance theneuromuscular elements that are now required fordynamic stabilization.

Because the shoulder complex encompasses severaljoints and a number of key structures, an in-depth dis-cussion regarding the epidemiology of shoulder dis-orders is beyond the scope or intent of this book.Instead, in the final section of this chapter we providean abridged review of several mechanical disorders ofthe shoulder commonly seen in the clinic, which aresubsequently detailed in later chapters. The intent ofthis condensed discussion is to encourage you to thinkabout both the impact that damage to these special-ized connective tissues might have in regard to func-tion and the objectives of treatment to restorefunction. The overview will include a brief discussionof the following topics:● Injuries to the acromioclavicular joint● Injuries to the sternoclavicular joint● Fractures of the proximal humerus● Instability of the glenohumeral joint● Disorders of the rotator cuff● Disorders of the biceps tendon● Arthritis of the glenohumeral joint

Consider the functional anatomy presented in thefollowing chapters in the context of these mechanicaldisorders. We hope you will gain an appreciation ofthe diversity of structures potentially responsible formechanical shoulder pain while being able to visitand revisit the clinical anatomy through the textand the accompanying DVD. Together, the text andDVD present a comprehensive view of the alterationin function that might occur as a result of thesedisorders.

Injuries to the AcromioclavicularJoint

We present a detailed view of the anatomy andmechanics of this joint in Chapter 4. As this anatomyis reviewed, consider how trauma to the point of theshoulder could displace the scapula and tear the sup-porting ligaments. When such trauma occurs, the nor-mal contour of the shoulder is lost as the upperextremity sags downward (Figure 1-11).


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In some shoulder conditions, especially after acuteinjuries to the acromioclavicular joint region or as aresult of repeated stress to the shoulder, the distal endof the clavicle can undergo demineralization andbony erosion.32

Finally, when you review the joint and understandits synovial joint characteristics, you can easily appre-ciate how degenerative joint disease may developinsidiously or as a sequelae to repair of the acromio-

clavicular joint. When reviewing the anatomy, notealso the relationship of the deltoid origins and trapez-ius insertions over the distal third of the clavicle andthe potential for soft tissue to become wedged betweenthe articulating surfaces of the joint.

Injuries to the SternoclavicularJoint

We discuss the mobility and stability of the ster-noclavicular joint, the articulation that literally sus-pends the upper extremity from the sternum, inChapter 4. The most common causes of sternoclavic-ular joint injuries are motor vehicle accidents andsports injuries, suggesting that trauma is a primarymechanism of injury.37 Posterior dislocations are ofspecial concern because of the relationship of themedial end of the sternum to the major blood vesselsand visceral structures such as the trachea and esoph-agus in the neck (Figure 1-12). Injuries include mildligamentous sprains, subluxations, dislocations, andarthritic degeneration of the articulating partners ofthe joint.

Finally, the epiphysis on the medial end of the clav-icle is the last epiphysis in the body to be seen on radio-graphs and it is the last to close. This epiphysis closesapproximately between the ages of 23 and 26, and soas you review the anatomy of this region, you needto remember that subluxations or dislocations may


Figure 1-11. The normal contour of the shoulder canbe changed as a result of downward force that displacesthe scapula.

SternumSternoclavicular joint

ClavicleCommoncarotid artery

Subclavianvein

Trachea

Lung

Esophagus

Vertebra

Rib

Subclavianvein

Subclavianartery

Innominateartery

Figure 1-12. A cross section of the thoraxshows the relationship of the medial end of theclavicle to the great vessels of the neck, tra-chea, and esophagus.

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not in fact be sternoclavicular joint injuries, but ratherepiphyseal plate injuries.51

Fractures of the Proximal Humerus

While studying the anatomy of the shoulder, it isimportant to keep in mind the different regions ofproximal humerus, including its anatomical neck, epi-physeal line, and surgical neck (Figure 1-13). Note theattachments of the joint capsule and capsular liga-ments (see Chapter 4), course of the peripheral nervesof the brachial plexus, especially the axillary nerve, inrelation to this region (see Chapter 2), attachments ofthe rotator cuff and course of the long head of thebiceps tendon (see Chapter 3), and course of the axil-lary artery (see Chapter 2). Injuries to the proximalhumerus and these associated tissues have the poten-tial to result in significant impairment with the conse-quence of disability.

Fractures of the proximal humerus are the mostcommon fractures associated with the humerus.43 Inmost cases these fractures occur as a result of falls andare a special concern in older adults since minimaltrauma is needed to result in fracture in the presenceof osteoporosis. Indeed, the incidence of proximalhumeral fractures markedly increases in adults over40 years of age. A careful review of the structuresassociated with this region provides us with a three-dimensional appreciation of its anatomy and the

implications for evaluation of the extremity and post-fracture management.

Instability of the GlenohumeralJoint

While the unstable nature of the glenohumeraljoint has long been discussed, it is only recently thatthe subtleties and complexities of that instability, espe-cially those multidirectional in nature, have becomeunderstood (see Chapter 4). The functions of differentportions of the capsule and the capsular ligaments act-ing as passive restraints have been coupled with a bet-ter understanding of the unique role of the rotatorcuff (see Chapter 3) acting as an active restraint.These two features now are linked to our increasedunderstanding of how afferent sensory input from thecapsular and muscle tissues ultimately dictates motoroutput to the support muscles of the shoulder.Furthermore, we have a better understanding of thecontribution of the scapulothoracic interface to main-tenance of glenohumeral stability. Successful evalua-tion and treatment of glenohumeral joint instabilityrelies on an integration of the neurologic, connectivetissue, and exercise sciences.

You should especially consider the orientation of theconnective tissue framework of the capsule and gleno-humeral ligaments and the intimate blending of thecuff tendons and the capsule when reviewing shoulder


Head

Anatomical neck

Surgical neck

Head

Anatomical neck

Surgical neck

Anterior Posterior

Figure 1-13. The anatomi-cal neck, surgical neck, andepiphyseal line of the proxi-mal humerus.

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anatomy. As pointed out in this chapter, once the con-nective tissue matrix has been compromised (break-down of the cellular bonding of the connectivetissues), static restraints cannot check aberrationalmotions. Trivial forces may result in abnormal trans-lations. It is at this point that exercise training of theneuromotor system becomes the key nonsurgical man-agement option. Elements of exercise training arereviewed in Chapters 2, 3, and 6.

Disorders of the Rotator Cuff

An extremely wide range of rotator cuff disordersexists, from uncomplicated inflammatory conditionsto full thickness tears. In addition, age-relatedchanges of the cuff tendons and weakness of therotator cuff markedly affect both glenohumeral sta-bility and shoulder function. It is important to care-fully study the cuff anatomy as presented in this text.The fiber orientation, muscle cross section, and rela-tionships to the fascial elements are of considerableimportance.

It also is helpful to visualize the intimate relation-ship that the cuff tendons have with the coracoacro-mial arch and how motion of the humerus results in agliding of the cuff tendons under this arch (Figure 1-14)(see Chapter 4). There are numerous exercises for theshoulder, but many can compromise the cuff tendonsby subjecting them to excessive compression, shear, ortension. You must consider the health and overallintegrity of the rotator cuff tendons when prescribingexercises; you need to envision the different stressesthat are placed on the tendons with any shoulder exer-cise (see Chapters 3 and 6).

Disorders of the Biceps Tendon

The two heads of the biceps tendon are unique intheir relationship to other shoulder structures. Forexample, carefully note how the short head of thebiceps contributes to the anterior aspect of the cora-coacromial arch (see Chapter 4). By comparison, alsofollow the relatively complex course of the long headof the biceps tendon. The long head is of great clin-ical importance and a prime culprit in impingementconditions. When studying the long head of thebiceps, follow the tendon superiorly over the proxi-mal shaft and head of the humerus, through the cap-sule and into the glenoid labrum, and observe its

unique position between the supraspinatus and sub-scapularis muscle attachments. This position places itimmediately deep to the coracohumeral ligament,the portion of the capsule referred to as the rotatorinterval, and the superior glenohumeral ligament(Figure 1-15).

In reality, the long head of the biceps tendon pre-sents as two different tendinous components: a morefibrous component of the tendon in the region of thebicipital groove that reduces the shear stress as thegroove slides back and forth under the tendon, and amore typical tendinous component designed to dissi-pate the tension associated with its attachment to theglenoid labrum and supraglenoid tubercle. Disordersof the tendon are variable and include uncompli-cated tendonitis, tenosynovitis (inflammation of thesheath covering the biceps tendon), mechanical com-promise of the tendon under the arch, and tendonrupture. Review the anatomy of the biceps tendonpresented here in the context of both painful syn-dromes and the potential loss of stability as a resultof tendon compromise.


Supraspinatus muscle

Biceps tendon(long head)

Superiorglenohumeralligament

Middleglenohumeralligament

Subscapularistendon

Axillary pouch

Teres minormuscle

Infraspinatusmuscle

Inferior glenohumeralligament complex(anterior band)

Inferior glenohumeralligament complex(posterior band)

Figure 1-14. The rotator cuff tendons blend intimatelywith the joint capsule, and this tissue blending is in closerelationship with the undersurface of the coracoacromialarch.

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Arthritis of the Glenohumeral Joint

Articular cartilage is a highly specialized class ofconnective tissue with very high tensile strength andresistance to compressive and shearing forces. At thesame time, it possesses some resilience and elasticity.The surface of articular cartilage is extremely smoothand relatively wear resistant, and when combined withsynovial fluid, it provides an exceptionally low coeffi-cient of friction between articulating surfaces. As seenin the other classes of connective tissue, it is thearrangement and types of specific proteoglycans, col-lagens, and cells, in association with water, that deter-mine the properties of cartilage. A change in one ofthe structural components will alter articular cartilagefunction and thus its capacity to accept the variousstresses placed on it.

Proteoglycans contribute between 30% and 35% ofthe dry weight of cartilage31 and form the majormacromolecule of the cartilage ground substance.The type of proteoglycans and the manner in whichthey are aggregated are important to the structural

rigidity of the extracellular matrix. In addition, theviscoelastic properties of cartilage depend on theconcentration of proteoglycans in solution.54

There is now good evidence that the structure andcomposition of the proteoglycans in articular cartilagechange with age.8 Because proteoglycans are impor-tant for maintaining cartilage stiffness, especially inregard to compression, and also contribute to theresilience of cartilage, an alteration in proteoglycancomposition reduces these qualities.24 This in turnalters the biomechanics of articular cartilage. It is thecyclic loading and unloading of the synovial joints thatsqueezes water out of and back into the cartilage,whereas the removal of pressure rehydrates it.22

This rehydration phenomenon contributes to car-tilage nutrition due to fluid changeover. Although carti-lage is described as an avascular structure, this is notentirely correct. What is actually meant is that the chon-drocytes are located at a greater distance from the circu-lation as compared with other tissues.53 Because of thisvascular limitation, the contribution by rehydration isimportant in maintaining the health of the chondrocyte.

The degenerative changes associated with the artic-ular cartilage affect its smoothness of movement andresult in the loss of stability of the glenohumeral joint(see Chapter 4). Degeneration of articular cartilage inthe humeral head typically manifests as centraldenudation surrounded by a rim of peripheral carti-lage and osteophytes. As a result of these cartilaginouschanges, the head of the humerus looks flat on radio-graphs and cartilage debris can often be found withinthe capsular recesses (Figure 1-16). The more com-mon anatomical findings associated with degenerativejoint disease of the glenohumeral joint are contractureof the anterior aspect of the capsule, posterior gleno-humeral subluxation, and central and posterior wearof the articular cartilage of the humeral head.12 Table1-2 lists a number of the important anatomicalchanges in the tissue associated with the glenohumeraljoint as a result of degenerative joint disease. As youreview the anatomy of the glenohumeral joint in thistext, give special consideration to the alteration infunction that might result as a consequence of articu-lar cartilage degeneration.

SUMMARY

We have briefly reviewed the science of connectivetissues and suggested how age, injury, and adaptivechange alter the capacity of specialized connective


Rotatorinterval

Figure 1-15. The long head of the biceps tendon is aunique structure. Note how the biceps tendon travelsover the head of the humerus between the subscapularisand the supraspinatus tendons. These tissues lie inferiorto the coracohumeral ligament. This area is referred toas the rotator interval.

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tissue to tolerate the various stresses on the shoulder.Once the integrity of a specialized connective tissue iscompromised, that tissue does not regenerate butinstead goes through a repair process, which leaves itless able to tolerate stress. The integrity of the con-nective tissue, coupled with the exquisite functioningof neuromotor elements, allows the shoulder to meetthe demands of mobility while simultaneously remain-ing stable. In the subsequent chapters we discuss thevarious aspects of functional shoulder anatomy indetail in order to provide an understanding about howthe shoulder meets these conflicting demands ofmobility and stability. We present a working knowl-edge of the anatomy of the region, coupled with anunderstanding of the expected responses of tissue toinjury, which is the basis for a logical progression ofevaluation and treatment including the formulation ofan exercise prescription.

REFERENCES

1. Akeson WH, Ameil D, Abel MF: Effects of immobilization onjoints, Clin Orthop 219:33,1987.

2. Akeson WH, Ameil D, La Violette D: The connective tissueresponse to immobility: an accelerated aging response, ExpGerentol 3:239, 1968.

3. Akeson WH, Ameil D, Woo SLY: Immobility effects of synovialjoints: the pathomechanics of joint contracture, Biorheology17:95, 1980.

4. Andersson GBJ: Epidemiology of occupational neck and shoul-der disorders. In Gordon SL, Sidney J, Blair MD, et al:Repetitive motion disorders of the upper extremity, Rosemont, Ill,1995, American Academy of Orthopaedic Surgeons.

5. Arem AJ, Madden JW: Effects of stress on healing wounds:intermittent non-cyclical tension, J Surg Res 20:93, 1976.

6. Bair GR: The effect of early mobilization versus casting onanterior cruciate ligament reconstruction, Trans Orthop Res Soc5:108, 1980.

7. Buckwalter JA, Cruess R: Healing of musculoskeletal tissues. InRockwood CA, Green D, editors: Fractures, Philadelphia,1991, JB Lippincott.

8. Buckwalter JA, Kuettner KE, Thonar EJM: Age-relatedchanges in articular cartilage proteoglycans: electron micro-scopic studies, J Orthop Res 3:251, 1985.

9. Buckwalter JA, Maynard JA, Vailas AC: Skeletal fibrous tissues:tendon, joint capsule, and ligaments. In Albright JA, BrandtRA, editors: The scientific basis of orthopaedics, Norwalk, Conn,1987, Appleton & Lange.

10. Burt S, Hornung R, Fine LJ: Health hazard evaluation report:National Institute of Occupational Safety and Health, HETA89:250, 1990.

11. Clancy WG: Tendon trauma and overuse injuries. InLeadbetter WB, Buckwalter JA, Gordon SL, editors: Sports-


Figure 1-16. Radiograph of glenohumeral joint withdegenerative joint disease. Because of the excessive thin-ning of the articular cartilage in the central region of thehumeral head, and the development of a peripheral rimof cartilage and osteophytes, the humeral head takes ona more “flattened” appearance. (Courtesy Rob Bell, MD,Crystal Clinic, Akron, Ohio.)

Table 1-2. Pathoanatomy of Arthritis of the Glenohumeral Joint

Changes Associated With the Humeral Head

Central cartilage erosion with flatteningCentral and superior sclerosisPeripheral osteophytes, especially inferiorlySubchondral bone cysts

Changes Associated With the Glenoid

Cartilage loss, especially centrally and posteriorlySclerosisPeripheral osteophytes, especially along inferior borderSubchondral bone cysts

Resting Joint Position

Posterior joint subluxation

Changes Associated With the Capsule

Anterior contractureInferior enlargement

Modified from Cofield RH: Degenerative and arthritic problems of theglenohumeral joint. In Rockwood CA Jr, Matsen FA III, Wirth MA, et al: Theshoulder, ed 2, Philadelphia, 1998, WB Saunders.

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induced inflammation: clinical and basic science concepts, Park Ridge,Ill, 1990, American Academy of Orthopaedic Surgeons.

12. Cofield RH: Degenerative and arthritic problems of the gleno-humeral joint. In Rockwood CA, Matsen FA III, editors: Theshoulder, Philadelphia, 1990, WB Saunders.

13. Cooper RR: Alterations during immobilization and regenera-tion of skeletal muscle in cats, J Bone Joint Surg Am 54(5):919,1972.

14. Cotton RE, Rideout DF: Tears of the humeral rotator cuff:a radiological and pathological necropsy survey, J Bone JointSurg Am 46:314, 1964.

15. Dehne E, Torp RP: Treatment of joint injuries by immediatemobilization: based on the spinal adaptation concept, ClinOrthop 77:218, 1971.

16. DeWitt MT, Handley CJ, Oakes BW, et al: In vitro response ofchondrocytes to mechanical loading: the effect of short-termmechanical tension, Connect Tissue Res 12:97, 1984.

17. Diamant J, Keller A, Baer E, et al: Collagen ultrastructure andits relation to mechanical properties as a function of ageing,Proc Roy Soc (series B) 180:293, 1972.

18. Eyre DR: Collagen: molecular diversity in the body’s proteinscaffold, Science 207:1315, 1980.

19. Frank CB, Hart DA: Cellular responses to loading. InLeadbetter WB, Buckwalter JA, Gordon SL, editors: Sportsinduced inflammation: basic science and clinical concepts, Park Ridge,Ill, 1990, American Academy of Orthopaedic Surgeons.

20. Fry, HJH: Occupational maladies of musicians: their cause andprevention, Int J Music Educ, 2:59, 1984.

21. Gelberman RH, Woo SLY, Lothringer K, et al: Effects of earlyintermittent passive mobilization on healing of canine flexortendons, J Hand Surg 7(2):170, 1982.

22. Gradisar IA, Porterfield JA: Articular cartilage, Top GeriatrRehabil 4:1, 1989.

23. Ham AW, Cormack DH: Histology, ed 8, Philadelphia, 1979, JBLippincott.

24. Harris ED Jr, Parker HG, Radin EL, et al: Effects of proteolyticenzymes on structural and mechanical properties of carti-lage, Arthritis Rheum 15:497, 1972.

25. Hirsch G: Tensile properties during tendon healing, Acta OrthopScand (suppl) 153:1, 1974.

26. Jenkinson ML, Bliss MR, Brain AT, et al: Peripheral arthritis inthe elderly: a hospital study, Ann Rheum Dis 48:227, 1989.

27. Kazar B, Relovsky E: Prognosis of primary dislocation of theshoulder, Acta Orthop Scand 40:216, 1969.

28. Klebe RJ, Caldwell H, Milam S: Cells transmit spatial infor-mation by orienting collagen fibers, Matrix 9:451, 1989.

29. Matsen FA III, Fu FH, Hawkins RJ: The shoulder: a balance ofmobility and stability, Rosemont, Ill, 1993, American Academyof Orthopaedic Surgeons.

30. Mosler E, Folkhard W, Knorzer E, et al: Stress induced molecularrearrangement in tendon collagen, J Molec Biol 182:589, 1985.

31. Muir IHM: The chemistry of the ground substance of jointcartilage. In Sokoloff L, editor: The joints and synovial fluid, vol2, New York, 1980, Academic Press.

32. Murphy OB, Bellamy R, Wheeler W, et al: Posttraumatic oste-olysis of the distal clavicle, Clin Orthop 109:108, 1975.

33. Nevasier RJ: Painful conditions affecting the shoulder, ClinOrthop 173:63, 1983.

34. Nordin M, Frankel VH: Biomechanics of collagenous tissues.In Frankel VH, Nordin M, editors: Basic biomechanics of theskeletal system, Philadelphia, 1980, Lea and Febiger.

35. Noyes FR: Fundamental properties of knee ligaments and alter-ations induced by immobilization, Clin Orthop 123:210, 1977.

36. O’Hara H, Aoyama H, Itani T: Health hazard among cash reg-ister operators and the effects of improved working condi-tions, J Hum Ergol (Tokyo) 5:31, 1976.

37. Omer GE: Osteotomy of the clavicle in surgical reduction of theanterior sternoclavicular dislocation, J Trauma 7:584, 1967.

38. Ozaki L, Fujimoto S, Nakagawa Y, et al: Tears of the rotatorcuff of the shoulder associated with pathologic changes inthe acromion: a cadaver study, J Bone Joint Surg Am 70:1224,1988.

39. Paulos LE, Tibone JE: Operative techniques in shoulder surgery,Rockville, Md, 1991, Aspen.

40. Porterfield JA, DeRosa C: Mechanical low back pain: perspectives infunctional anatomy, ed 2, Philadelphia, 1998, WB Saunders.

41. Porterfield J, DeRosa C: Mechanical neck pain: perspectives in func-tional anatomy, Philadelphia, 1995, WB Saunders.

42. Punnett L, Robins JM, Wegman DH, et al: Soft tissue disordersin the upper limbs of female garment workers, Scan J WorkEnviron Health 11:417, 1985.

43. Rose SH, Melton LJ, Morrey BF: Epidemiologic features ofhumeral fractures, Clin Orthop 168:24, 1982.

44. Shah JS, Jayson MIV, Hampson WGJ: Low tension studies ofcollagen fibers from ligaments of the human spine, AnnRheum Dis 36:139, 1977.

45. Simon WH: Soft tissue disorders of the shoulder, Orthop ClinNorth Am 6:521, 1975.

46. United States Department of Labor, Bureau of LaborStatistics: Survey of occupational injuries and illnesses, Washington,DC, 1994, U.S. Department of Labor.

47. Uitvlugt G, Detrisac DA, Johnson LL, et al: Arthroscopic obser-vations before and after manipulation of the frozen shoulder,Arthroscopy 9:181, 1993.

48. van Schaardenburg D, Van den Brande KJ, Ligthart GJ, et al:Musculoskeletal disorders and disability in persons aged 85and over: a community survey, Ann Rheum Dis 53:807, 1994.

49. Videman T: Connective tissue and immobilization: key factors inmusculoskeletal degeneration? Clin Orthop Rel Res 221:26, 1987.

50. Wahls SM, Renstrom P: Fibrosis in soft-tissue injuries. InLeadbetter WB, Buckwalter JA, Gordon SL, editors: Sports-induced inflammation: clinical and basic science concepts, Park Ridge,Ill, 1990, American Academy of Orthopaedic Surgeons.

51. Webb PAO, Suchey JMM: Epiphyseal union of the anterior iliaccrest and medial clavicle in a modern multiracial sample ofAmerican males and females, Am J Phys Anthropol 68:457, 1985.

52. Welsh RP, MacNab I, Riley V, et al: Biomechanical studies ofrabbit tendon, Clin Orthop 81:171, 1971.

53. Williams PL, Warwick R: Gray’s anatomy, ed 36 (Br),Philadelphia, 1986, WB Saunders.

54. Woo SLY, Buckwalter JA: Injury and repair of the musculoskeletal softtissues, Park Ridge, Ill, 1988, American Academy ofOrthopaedic Surgeons.

55. Woo SLY, Debski RE, Boardman ND, et al: Pathophysiology ofinjury and healing. In Hawkins RJ, Mismore GW, editors:Shoulder injuries in athletes, New York, 1996, ChurchillLivingstone.

56. Woo SLY, Ritter MA, Amiel D, et al: The biochemical and bio-mechanical properties of swine tendons: long term effect ofexercise on the digital extensors, Connect Tiss Res 7:177, 1980.


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INTRODUCTION

Mechanical stresses and loads potentially can injurespecialized connective tissues of the shoulder (seeChapter 4). The pain felt at the shoulder as a result ofmechanical stresses is often due to the physical distortionof nociceptors that lie within these tissues or is a conse-quence of chemical activation of the resident nocicep-tive free nerve endings that are depolarized as a result ofdamage to the cell walls of the tissues. Nociceptors arethe biological transducers that convert physical andchemical energy stimuli into action potentials.

In addition to injury to the specialized connectivetissues or damage to the musculotendinous tissues,pain felt within the shoulder may be caused by severalother neuroanatomical or neurophysiological factors.These include nerve root irritation of nociceptors thatlie within these tissue. It may also be a consequence ofchemical activation of the resident degenerative jointdisease or spondylosis of the cervical spine, compro-mise to the brachial plexus along its path through the

axilla, and damage or irritation to the peripheralnerves that supply the various tissues of the region.

In addition to their potential for shoulder pain,nerve root disorders or peripheral nerve injuries areespecially complex because these disorders typicallychange the function of the shoulder. Altered neuralinput to and from the shoulder girdle as a conse-quence of nerve root compromise results in abnormalosteokinematics of the humerus on the glenoid,scapula on the clavicle, clavicle on the sternum, orscapula on the thoracic cage. These altered movementpatterns further compromise the various innervatedtissues of the shoulder region, which results in othertissue sources of pain, potentially confounding thefindings in the shoulder examination.

In this chapter we want to provide the reader with anunderstanding of the relationships between the differentcomponents of the nervous system relative to the shoul-der rather than provide an exhaustive review of the neu-roanatomy and neurophysiology of the upper quarter.Our intent is to discuss the neuroanatomical and neuro-physiological implications in a practical, clinical sense.We cover the conditions that refer pain to the shoulder,analyze the peripheral nerves that are key to supplyingthe shoulder complex and their associated clinical con-ditions, and finally, explore the integrated role of thesensory and motor systems as both relate to shoulderfunction and the establishment of treatment regimensfor shoulder disorders. Restriction of function, which in

CHAPTER 2NEUROANATOMICAL AND NEUROMECHANICALASPECTS OF THE SHOULDER

21

DVDThroughout this chapter you will find small circular icons marked

“DVD” (see margin). These icons identify content that is coordi-nated with a video clip on the DVD accompanying this text. Formaximum learning benefit, go to the “Text Reference Section” onthe DVD and play the coordinated clip while reading the appropri-ate section of text. These clips expand on and reinforce the infor-mation presented in the text.

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reality is neural driven, is the primary reason to treatpainful disorders of the shoulder.

In the following sections we discuss shoulder painthat might be due to pathology associated with thecervical spine first. After that we detail the anatomyand clinical implications of the peripheral nerves.Finally, we explain sensorimotor integration as itrelates to shoulder function and intervention.

THE CERVICAL SPINEAND SHOULDER PAIN

We limit the involvement of the cervical spine rela-tive to shoulder disorders to two clinical syndromes:pain and dysfunction as a result of the mechanical orchemical irritation of the cervical nerve root, andreferred pain from the musculoskeletal tissues of thecervical spine itself. The cervical nerve roots extendfrom the cervical spinal cord via a series of nerverootlets (Figure 2-1). The dorsal root is primarily affer-ent (transmitting information toward the spinal cord),whereas the ventral root is primarily efferent (trans-mitting information from the spinal cord toward theperiphery). Consequently, the dorsal root is consideredthe sensory nerve root, whereas the ventral root is con-sidered the motor nerve root. The sensory nerve rootsof the cervical spine are relatively large and feature anextensive array of nerve rootlets because of the

breadth of the receptor system associated with theupper extremity.

The nerve roots are invested with pia mater, bathedin cerebrospinal fluid, and covered by the arachnoidand dura mater. At approximately the region of theintervertebral foramen, the nerve roots merge to forma very short spinal nerve, after which the spinal nerveimmediately breaks into two branches—the dorsalramus and the ventral ramus (Figure 2-2).

The dorsal ramus branches over the posterioraspect of the neck, supplying the deep muscles of thecervical spine and the skin. The ventral ramus arisesfrom several cervical and thoracic segments and ulti-mately merges with the dorsal ramus to form the prox-imal components of the brachial plexus. The brachialplexus is therefore the primary nerve source for theshoulder and upper extremity. It carries both motorand sensory supply to and from the tissues respectively.We will focus on the nerve roots here because theypotentially relate to shoulder pain and will discuss thebrachial plexus in detail later in the chapter.

The dorsal roots of the cervical and upper thoracicspinal cord levels are responsible for specific regions ofthe skin (dermatomes), bones (sclerotomes), and muscles(myotomes). The areas of skin innervated by peripheralcutaneous nerves are supplied by the axons stemmingfrom specific cervical and upper thoracic nerve roots,and the representation of these root segments on theskin can be reasonably mapped (Figure 2-3). Note that

22 NEUROANATOMICAL AND NEUROMECHANICAL ASPECTS OF THE SHOULDER

Spinalcord

Dorsalrootlets

Dorsal root ganglion

Figure 2-1. The cervical nerve roots areformed from a series of dorsal and ventralrootlets, which are attached to the spinalcord. These rootlets come together andultimately form the dorsal and ventralroots for each cervical segment.

DVD

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NEUROANATOMICAL AND NEUROMECHANICAL ASPECTS OF THE SHOULDER 23

DVD

Duramater

Dorsalrootganglion

Ventralramus

Dorsalramus

Ventralnerverootlets

SPINAL CORD

Figure 2-2. The dorsal and ventralnerve roots come together to form thespinal nerve, and almost immediately thespinal nerve divides into its two compo-nents: the posterior primary ramus andthe ventral primary ramus.

C3C2

C4

C5 C5

C6 C6

C7 C7C8C8

C8C6

T2T3T4T5

T6

T7

T1T1

T2 T2

C3

C4C5C6

T3T2 T2

T2T2

T1 T1

C5 C5T4T5T6T7

C7 C8 C6C7

Figure 2-3. The area of skin supplied by the cervical and upper thoracic nerve roots is referred toas the dermatomal distribution of the nerve roots around the shoulder.

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in regard to sensory supply, the nerve roots representedin the immediate shoulder region are primarily C4, C5,and C6. The fourth cervical nerve root (C4) is typicallylimited in distribution to the top of the shoulder (thearea surrounding the acromioclavicular joint), whereasthe fifth and sixth cervical nerve roots supply the major-ity of the shoulder area. In addition, the first thoracicdorsal nerve root (T1) is represented in the upper medialaspect of the arm and the axilla. The T1 ventral root isunique because it carries the first spinal cord level of thepreganglionic neurons associated with the sympatheticnervous system. After these preganglionic neurons com-municate with the sympathetic chain, located immedi-ately adjacent to the spinal nerve, the ventral and dorsalrami of T1 then carry the postganglionic neuronsperipherally to the smooth muscle, cardiac muscle, andglands of the upper extremity and face (Figure 2-4).

In the neck, the most common level of nerve rootinvolvement is the middle and lower cervical spine—theC4-C5, C5-C6, and C6-C7 spinal segments. These cer-vical vertebral levels typically show earlier degenerativechanges than the other regions of the cervical spine. The

fifth cervical nerve root (C5) exits between the fourthand fifth cervical vertebrae, whereas the sixth cervicalnerve root (C6) exits between the fifth and sixth cervicalvertebrae (Figure 2-5). It is primarily these two nerveroots (C5 and C6) that are represented in and aroundthe shoulder girdle. These nerve roots are responsible forthe largest portion of the sensory feedback from theshoulder to the central nervous system (CNS) and themajority of motor supply to the shoulder musculature.

While several pathoanatomical changes in the cervi-cal spine can compromise the nerve roots, the two mostcommon are intervertebral disc pathology and degen-erative joint disease of the apophyseal joints. Becausedegenerative changes of the disc and the joints areoften related to age, it is important that the clinicianrule out cervical nerve root involvement in the middle-age or older adult patient who presents with shoulderpain. In such patients a nerve root screen is an essentialcomponent of the shoulder evaluation (Table 2-1).

A differential diagnosis may be made based on sev-eral features of nerve root pain. The quality of nerveroot pain is different from pain from other tissues about


Preganglionicneuron

Dorsal rootganglion

Paravertebralchain ganglion

Postganglionicneuron

Postganglionicfiber

To the cervicalganglion

T1

T2

Sympatheticnerve trunk

Figure 2-4. The T1 ventral nerve root carries preganglionic nerve fibers from the first level of thesympathetic nervous system. Postganglionic neurons are then distributed from the sympathetic chainganglion through the ventral and dorsal ramus.

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the shoulder, typically being sharper, more highly local-ized, and very disconcerting to the patient. The pain isfelt deep throughout the upper extremity, usually in aclearly demarcated zone. Oftentimes the patient pres-ents with shoulder and neck pain, but the extremitypain is typically more distressing than the pain in thecervical spine. The presence of proximal pain and dis-tal paresthesias in the upper extremity is another hall-mark of nerve root involvement. For example, C5nerve root involvement is often manifested by upperarm and shoulder pain and elbow paresthesias.

Irritation of the C6 nerve root is associated with paintoward the anterior elbow and paresthesias over theradial aspect of the forearm and thumb.

Whereas nerve root irritation may be related to painwithin the shoulder region, nerve root compression is amore significant disruption of sensory or motor axonfunction and as such may alter sensation throughout theshoulder region or result in motor changes. Such motorchanges are manifested as weakness, atrophy, or alteredreflexes. Table 2-2 lists the nerve root segments that aretypically represented in the key muscles associated withthe shoulder. Note the large distribution of the fifth andsixth cervical nerve roots throughout the musculature ofthe shoulder. When assessing the integrity of the C5and C6 nerve roots, testing the muscles is an importantpart of the clinical examination, especially the shoulderabductors, shoulder external rotators, and the bicepsbrachii. Reflex testing of the biceps also provides dataregarding the status of the nerve roots. Involvement ofthe C7 nerve root does not typically cause shoulderpain, but if suspected, is best assessed through muscletesting the triceps brachii and its reflex.

The second example of cervical spine involvementthat can lead to shoulder pain is referred pain fromnon–nerve root structures such as the cervical apophy-seal joints and the soft tissues related to the cervicalspine. Referred pain from the cervical spine to theshoulder is another clinical manifestation that must beconsidered in the examination of the patients present-ing with shoulder pain. The neuroanatomical pathway


Occipital bone

Atlas

2

FM

C1

C2

C4

C6

C7

C8

T1

C3

C5

3

4

5

6

7

T1

Figure 2-5. Spinal nerves are named for the junctionpoints where the ventral and dorsal roots merge in thecervical spine.

Table 2-1. Elements of the Nerve RootScreen for the Patient Presenting

With Shoulder Pain

1. Quadrant testing of neck: Does this cause radiation into thearm?

2. Foraminal compression test (Spurling’s test)3. Reflex testing of the upper extremity

a. Biceps: C5b. Brachioradialis: C6c. Triceps: C7

4. Muscle testinga. Shoulder abduction: C5b. Elbow flexion: C6c. Elbow extension: C7d. DIP thumb extension: C8e. Abduction-adduction of fingers: T1

Table 2-2. Nerve Root Supply to Musclesof the Shoulder

Muscles Nerve RootsPectoralis major C5, C6, C7, C8, T1Pectoralis minor C7, C8, T1Deltoid C5, C6Supraspinatus C5, C6Infraspinatus C5, C6Teres minor C5, C6Subscapularis C5, C6Trapezius XI, C3, C4Serratus anterior C5, C6, C7Latissimus dorsi C6, C7, C8Teres major C5, C6Levator scapulae C3, C4Rhomboid major C5Rhomboid minor C5Coracobrachialis C5, C6, C7Biceps brachii C5, C6Triceps brachii C6, C7, C8

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for referred pain is difficult to precisely define. Cyriaxdescribes referred pain as “pain felt elsewhere than atits true site.”7 Although this definition is adequate as aworking clinical description, it only describes the phe-nomenon as perceived by the patient and observed bythe clinician. It is not a neurophysiological description.

The CNS, rather than the peripheral nervous sys-tem, is largely responsible for the manifestation andinterpretation of referred pain. As stated by Grieve,“pain happens within the CNS, and does not reside inthe damaged locality, though it may be perceivedso.”18 He is telling us that the subjective experience ofpain is the result of processing the afferent impulse atthe spinal cord, brainstem, and cerebral cortex levels.The painful stimulus activates many pools of neuronsat all levels of the CNS, all of which contribute to theperception of referred pain.

Several tissues of the cervical spine have commonreferral patterns to the shoulder. For example, theapophyseal joints of the C4-C5 or C5-C6 vertebralsegments have a characteristic referral pattern to the

shoulder in addition to the primary complaint of neckpain. Figure 2-6 illustrates the areas of the shouldertypically involved with referred pain from the cervicalapophyseal joints.1,14

Discogenic pain, thought to arise from the break-down of the disc at these same levels, may also be asource of referred shoulder pain. Finally, the cervicalmuscles associated with these same cervical segmentallevels have the potential to refer pain into the shoulderregion, most commonly over the scapula. We think thatreferred pain from degenerative joint disease of theapophyseal joints of the cervical spine is the more com-mon mechanism of referred shoulder pain. The palpa-ble changes in muscle tension about the neck and thescapula are reflex responses of the neuromuscular sys-tem as a result of injury or degenerative breakdown ofthe specialized connective tissues of the cervical spine.

As discussed earlier, careful examination of the cer-vical spine in the middle-age or older adult patientcomplaining of shoulder pain is important in linkingthe contribution of the cervical spine to the painfulsyndrome being examined because primary degenera-tive joint disease is an age-related phenomenon.A quick screen of the cervical spine to reproduce thepain described typically includes endrange rotationand testing the cervical spine in the extension quad-rants (Figure 2-7).

Finally, the clinician should bear in mind that vis-ceral structures also have the potential to refer pain tothe shoulder. Pain felt in the shoulder region can becaused by gallbladder disease, disorders of thediaphragm, disorders of the spleen, and pathology ofthe heart or lungs. Mechanical disorders of the mus-culoskeletal system, however, often feature a pattern ofpain and can be provoked with mechanical stresses,which is atypical of visceral disorders. In the absenceof a predictable pain pattern, and when familiar signsor symptoms cannot be elicited through the applica-tion of mechanical stresses to the shoulder tissues orcervical spine in the examination (see Chapter 5),additional diagnostic tests are necessary to rule outpain of visceral origin.

THE BRACHIAL PLEXUS

The ventral rami of C5, C6, C7, C8, and T1 inter-weave to form the brachial plexus, which gives rise tonearly the full complement of sensory and motornerves associated with the upper extremity (Figure 2-8).The plexus is best studied when divided into its


C3-4

C2-3

C4-5

C6-7

C5-6

Figure 2-6. The cervical apophyseal joints can referpain toward the shoulder region. This illustration showsthe region of the shoulder in which such pain may beperceived by the patient. (Modified from Dwyer A, April C,Bogduk N: Cervical zygapophyseal joint pain patterns I:a study of normal volunteers, Spine 15(6):453, 1990.)

DVD

DVD

DVD

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Figure 2-7. Since disorders of the apophyseal joints of the cervical spine (especially segments C4-C5 and C5-C6) can refer pain to the shoulder, we include a cervical screening in the examina-tion of the patient with shoulder pain, especially middle-age or older adults. In view A, the exam-iner brings the cervical spine to endrange rotation, and in B, the examiner brings the cervical spineinto the extension quadrant. When the examiner is able to reproduce familiar neck and shoulderpain with these maneuvers, it suggests that the shoulder pain is referred from the cervical spine.(From Porterfield JA, DeRosa C: Mechanical neck pain: perspectives in functional anatomy, Philadelphia,1995, WB Saunders.)

A

B

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component parts: the ventral rami, trunks, divisions,cords, and peripheral nerve branches.

The area of the neck that lies above the clavicle iscalled the supraclavicular region. It is in this regionthat the proximal parts of the brachial plexus arelocated. In addition to the ventral rami, there are threetrunks. The upper trunk is formed when the fifth andsixth ventral cervical rami unite. The eighth cervicaland first thoracic ventral rami form the lower trunk ofthe brachial plexus, and the ventral ramus of C7 con-tinues as the middle trunk.

Injury to the trunks of the brachial plexus can resultfrom trauma. The classic “burner” or “stinger” injuryto the shoulder, often seen in athletes who play footballor wrestle, usually is a result of a forced depression ofthe scapula on one side in combination with lateralflexion of the cervical spine to the contralateral side.The combination of these forces to the neck and shoul-der girdle results in a stretch injury to the upper trunk

of the brachial plexus (Figure 2-9). While pain fromsuch an injury is often immediate, associated neurolog-ical changes in the muscles ultimately supplied bynerve branches of the upper trunk or its continuationmight not be evident until several days after injury. Asmight be expected, injuries to the upper trunk of thebrachial plexus can affect deltoid, supraspinatus, infra-spinatus, and biceps brachii muscles.6,9

Each trunk of the brachial plexus gives rise to ante-rior and posterior divisions. The posterior divisions fromthe upper, middle, and lower trunks ultimately merge toform the posterior cord of the brachial plexus, whereas theanterior divisions of the upper and middle trunk formthe lateral cord. The anterior division of the lower trunkcontinues as the medial cord. The cords of the brachialplexus are named for their relationship (medial, lateral,or posterior) to the axillary artery (Figure 2-10).

Although some of the peripheral nerves that ulti-mately supply the skin and muscles of the upper


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Lateral pectoral nerve

Musculocutaneous nerveAxillary nerveRadial nerve

Median nerve

Ulnar nerveMedialcutaneousnerve of arm

Medial cutaneousnerve of forearm

Lower subscapular nerve

Thoracodorsal nerve

Upper subscapular nerve

Medial pectoral nerve

First intercostal nerve

From T2

T1

To scalene

C8

To scalene

To subclaviusTo scalene

To phrenic nerve

From C4

C7

C6

C5

Long thoracic nerve

Dorsal scapular nerve

Suprascapular nerve

Figure 2-8. The brachial plexus.

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Figure 2-9. The mecha-nism of the “stinger” injuryshown here is a result offorced depression of thescapula on one side in combi-nation with lateral flexion ofthe neck to the opposite side.

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Brachial plexus

Subclavian artery

Figure 2-10. The cords ofthe brachial plexus are namedfor the axillary artery becauseof their relationship to thisprimary source of blood to theshoulder region.

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Brachial plexus

Subclaviusmuscle

Middle scalenemuscle

Anterior scalenemuscle

Figure 2-11. This illustra-tion shows the relationshipbetween the intervertebralforamen and scalene mus-cles to the ventral rami ofthe brachial plexus.

extremity branch from the trunks and divisions of theplexus, most of the peripheral nerves branch from thecords. Note that the interweaving of the rami, trunks,divisions, and cords results in the potential for many ofthe peripheral nerves to carry several different nerveroot segments ranging from C5 through T1. Figure 2-8 illustrates the peripheral nerves that branch from thebrachial plexus.

Physiological Relationshipsof the Brachial Plexus

The brachial plexus (rami, trunks, divisions, cords,and branches) travels over a fairly complex route in itspath from the anterolateral aspect of the cervical spineto the arm. Thus, you need to have a general idea ofthe relationships of the various components of thebrachial plexus to important cervical and shoulder gir-dle structures. From their position lateral to the nerveroots, the ventral rami lie just outside the intervertebralforamen positioned between the anterior and middlescalene muscles (Figure 2-11). The trunks of the plexuslie anterior to the levator scapulae muscle and coursebetween the anterior and middle scalene musclestoward the upper posterior aspect of the clavicle. Atthis region, the neural tissue of the brachial plexus is

incorporated into the fascial sheath of the scalenes,which allows injections of local anesthetic to be con-tained within the immediate environs when given as atreatment intervention.

The upper two rami join together to form the uppertrunk at Erb’s point. This landmark can be visualizedas lying 2 to 3 cm above the clavicle immediately pos-terior to the sternocleidomastoid muscle (Figure 2-12).The lower trunk, in contrast, forms behind the clavi-cle directly above the pleura of the lung. Thus apicallung tumors can compromise neural function of thelower trunk of the brachial plexus and must be ruledout when evaluating sensory and motor disturbancesof the upper extremity of unknown etiology.

Approximately at the level of the clavicle, the trunkssplit into anterior and posterior divisions. Branchesemerging from the anterior division supply the flexorsof the upper extremity, whereas branches from theposterior division primarily supply extensors. At thispoint, however, these components of the brachialplexus lie within the costoclavicular space and passinto the infraclavicular region (Figure 2-13).

After passing between the clavicle and rib and thenunder the pectoralis minor muscle, the plexus reachesthe axilla, where it is thoroughly invested with axillaryfascia and protected by the fat, connective tissue, andlymph nodes of the axilla. In this region the cords of

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the brachial plexus are formed and lie in close approx-imation to the axillary artery. The peripheral nervesthat carry the alpha and gamma motor neurons thatsupply the extrafusal and intrafusal muscle fibersrespectively, and the sensory nerves that not only carrynociceptive and general sensation but also propriocep-tive feedback from the upper extremity to the CNS,emerge from the axillary fascia.

Key Peripheral Nerves of theBrachial Plexus and RelatedClinical Syndromes AssociatedWith the Shoulder

Suprascapular Nerve

The suprascapular nerve branches from the uppertrunk of the brachial plexus at Erb’s point and typi-cally carries the fifth and sixth cervical nerve roots. Its

route toward the two muscles it supplies, thesupraspinatus and infraspinatus, is unique because ittravels through the suprascapular notch of thescapula, which is bridged by the transverse scapularligament.34 The suprascapular artery lies superior tothis ligament, whereas the suprascapular nerve travelsinferior to it (Figure 2-14). Note that the suprascapu-lar nerve does not move within the notch, but instead,it is the scapular notch that must move relative to thenerve. This scapular motion occurs over the scapu-lothoracic interface and acromioclavicular joint.

On entering the supraspinous fossa, the nervesupplies the supraspinatus muscle and then courseslaterally to supply sensory branches to the acromio-clavicular joint and the posterior aspect of the jointcapsule. Then the suprascapular nerve swings aroundthe spine of the scapula to enter the infraspinous fossaand supply the infraspinatus muscle. In the supra-spinous fossa, branches of the suprascapular nervesupply the acromioclavicular joint and the superior


Sternocleidomastoidmuscle

Erb’s point

Figure 2-12. Erb’s point is the junction of theupper two rami and is typically 2 to 3 cm abovethe clavicle and immediately posterior to the ster-nocleidomastoid muscle.

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aspect of the glenohumeral joint. In the infraspinousfossa its branches extend to the posterior aspect of theglenohumeral joint.

The suprascapular nerve can be injured or compro-mised in several ways.11,13,30 Grade III sprains of theacromioclavicular joint (see Chapter 4) can result intraction to the suprascapular nerve as a result ofdownward displacement of the scapula and the result-ant compression and traction to the nerve by the over-lying transverse scapular ligament (Figure 2-15).34

Since the suprascapular nerve is relatively fixed atits origin from the upper trunk and at its terminationin the infraspinous fossa, it can be injured via tensilestresses, which might occur with excessive range ofscapular motions so common in many athletic activi-ties, such as swimming, tennis, and throwing.5,30 Tryto visualize how the distance between the two ends ofthe nerve increases with scapular motions and howrepetitive motion of the scapula continually “rides”the suprascapular notch back and forth under thenerve. Repetitive carrying of heavy loads that forcesthe scapula into extremes of depression also mayresult in traction to the nerve.2,3 The location of the

suprascapular nerve as it crosses the posterior aspect ofthe glenohumeral joint may render it vulnerable toposterior glenohumeral subluxations and dislocation.Compression by ganglion cysts or neoplasms in theregion of the spinoglenoid notch or posterior capsulealso may cause pathology.42

Although the anatomical course of the nerve andanalysis of scapular motion suggest ways in which thesuprascapular nerve can be injured, it is often difficultto make a clinical diagnosis. Pain is typically felt pos-terior and is poorly localized. Depending on theregion of the nerve compromised, weakness and atro-phy of the supraspinatus and infraspinatus may bepresent. Compromise at the spinoglenoid notch wouldaffect only the infraspinatus because innervation ofthe supraspinatus occurs proximal to this point.

Typically, infraspinatus atrophy is easier to detectthan supraspinatus atrophy. Weakness of thesupraspinatus and infraspinatus muscles has an impacton arm elevation, abduction, and external rotation.Note, however, that weakness of these muscles can becaused by a variety of other conditions, such as rota-tor cuff tears or cervical nerve root involvement.


Figure 2-13. This illustrationshows the relationship between thedivisions of the brachial plexus tothe costoclavicular space.

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Diagnosis of suprascapular neuritis is therefore verydifficult. Electromyography of these two muscles mayhelp confirm the diagnosis. Treatment usually focuseson rest, limiting the range of scapular motion withactivity, support of the scapula if possible to avoid itbeing displaced inferiorly, and scapula elevation exer-cises in a moderate range.

Finally, the suprascapular nerve is one of the nervesthat supply the glenohumeral joint capsule. Stimulationof the suprascapular nerve endings in the joint capsulehas demonstrated contractile activity of the biceps,infraspinatus, supraspinatus, and subscapularis musclesin the feline model, implying that reflex arcs exist fromthe ligaments and joint capsule to their associated mus-cles.40 It is reasonable to suspect that motions of thejoint, especially those that take the connective tissues toranges resulting in activation of the nerve endings in thecapsule, trigger muscle contractions, which stabilize andkeep the humerus centered on the glenoid.

Long Thoracic Nerve

The long thoracic nerve, originating from the C5, C6,and C7 ventral rami at the level of the intervertebralforamen, is one of the few nerves in the body thatcourses on the external surface of the muscle it

innervates (Figure 2-16). The serratus anterior lies super-ficially on the lateral chest wall, which appears to placethe nerve in a fairly vulnerable position but, in fact, thenerve is adequately protected by soft tissues in its course.The common mechanisms of injury are direct traumato the lateral chest wall or traction stresses to the nerve.Traction of the nerve occurs primarily with scapularretraction and depression since this maneuver stretchesthe nerve over the first rib. The particular region of thenerve most vulnerable to this stretch is between theupper part of the serratus anterior and the lower borderof the middle scalene (Figure 2-17).

The large excursion of scapulothoracic motion seenin numerous sports has been documented as havingthe potential to injure the long thoracic nerve.Bowling, throwing, discus, football, golf, gymnastics,weightlifting, and wrestling have all been impli-cated.16,17,46 Activities in which the arm is vigorouslypulled into abnormal positions also may result in thescapula moving in a direction that causes traction tothe nerve.21 Like many of the peripheral nerves, longthoracic nerve palsy can occur as a result of viralinfection of the nerve, infections, and lower motorneuron disease.46

The serratus anterior is the key upward rotator ofthe scapula, and weakness caused by long thoracic


Suprascapular artery

Suprascapular nerve

Superior transverse scapular ligamentand suprascapular notch

Acromion

Supraspinatus muscle

Spine of scapula

Infraspinatus muscle

Figure 2-14. The supra-scapular nerve branches fromthe upper trunk of the brachialplexus and travels posteriorlyto run through the supra-scapular notch, where it liesunder the transverse scapularligament. After passing throughthe notch, it supplies thesupraspinatus muscle and thenswings laterally around thespine of the scapula to supplythe infraspinatus muscle. Inaddition to supplying thesetwo muscles, this nerve alsosupplies the posterior aspect ofthe joint capsule and the acro-mioclavicular joint.

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nerve damage impairs its ability to strongly lift thearm overhead since the scapulothoracic contributionto arm elevation is lost. The strong attachment of thismuscle to the medial wall of the scapula will result inthe medial border of the scapula losing contact withthe chest wall—the classic “winging” scapula—whenthere is a loss of resting muscle tension as a result ofnerve palsy (Figure 2-18).

If traction to the nerve is considered to be the eti-ological factor, postures that potentiate the nervetension via stretch of the serratus anterior (markedretraction and downward rotation of the scapula)must be avoided. Stretching of the muscles that arescapular protractors, such as the pectoralis majorand pectoralis minor, may also contribute to pos-tural correction. Like most upper quarter problemsthat have postural mechanics as an etiological factor,strengthening of the scapulothoracic and abdominalmuscles is essential for postural balance. Recoveryfrom nerve palsy is typically slow, often taking aslong as 2 years.

Axillary Nerve

The axillary nerve carries the C5 and C6 nerve rootsegments and is one of the terminal branches of theposterior cord of the brachial plexus. It is an often-injured nerve.22 In addition to supplying the three del-toid heads and the teres minor muscle, it suppliessensory innervation to the shoulder joint capsule andcutaneous sensation about the shoulder. The otherterminal branch is the radial nerve.

Once you understand the course of the axillarynerve, you can visualize its potential for injury. Fromits position on the surface of the subscapularis muscle,it travels posteriorly to the inferior aspect of the shoul-der joint capsule28 (see Figure 2-12). It gains the pos-terior position of the shoulder by emerging from thequadrilateral space (Figure 2-19), whereupon itbranches into anterior and posterior components tosupply the deltoid and teres minor muscles and theskin over the region of the lateral arm via its promi-nent cutaneous branch, the lateral brachial cutaneousnerve. The anterior branch of the axillary nerve is alsoresponsible for the sensory supply to the lower portionof the glenohumeral joint capsule, and on emergingfrom the quadrilateral space, the posterior branch alsocontributes to the sensory supply of the glenohumeraljoint capsule. These two branches of the axillary nerveconstitute the major nerve supply of the glenohumeraljoint capsule.15

Because of its close relationship to the proximalend of the humerus, the axillary nerve is vulnerableto stretch injuries secondary to dislocations or frac-tures of the humerus, and its close proximity to theinferior aspect of the joint capsule renders it vulnera-ble during surgical procedures designed to tighten thejoint capsule for glenohumeral joint instability prob-lems.29a These articular branches of the axillarynerve have also been found to elicit contractions inthe biceps, subscapularis, supraspinatus, and infra-spinatus muscles when experimentally stimulated.20

This implies a synergistic relationship between pas-sive support structures (capsule and ligaments) andthe neuromuscular system.

The most common mechanism of injury to thenerve occurs during anterior dislocations of thehumerus. Estimates of the incidence of axillary nerveinjury following dislocations range from 10% to 18%.4

Axillary nerve injury has also been documented inconditions arising from carrying heavy packs on theshoulders, forcing the shoulder girdle into prolongedand excessive depression.24,36 Signs and symptoms


Suprascapularnerve

Acromioclavicularseparation

Figure 2-15. When the scapula is subluxed or dislo-cated from the clavicle at the acromioclavicular joint, it isdisplaced downward and rides inferiorly, resulting intraction to the suprascapular nerve, and the nerve iscompressed against the lower border of the thick trans-verse scapular ligament.

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associated with axillary nerve injury include weaknessof the deltoid and altered sensation about the shoul-der, electromyographic (EMG) changes, pain over theregion of the quadrilateral space, and diffuse aching inthe shoulder joint especially after use. Because thenerve is relatively short in its course around thehumerus, the prognosis for recovery is good.Maintaining strength and range of motion, especiallyin the rotator cuff and scapulothoracic muscle groups,is important in this recovery phase.

Spinal Accessory Nerve

The spinal accessory nerve is the name for cranialnerve XI with its associated cervical contributions. It isa complex nerve and originates in the cervical spinalcord and medulla. The axons of the cervical cord ori-gin ascend through the foramen magnum to join itscounterpart from the medulla in its formation, and theconjoint axons descend to exit through the jugularforamen located at the base of the skull (Figure 2-20).After passing through the sternocleidomastoid musclethat it also innervates, the spinal accessory nerve

travels posteriorly to reach and supply the trapeziusmuscle on its deep surface (Figure 2-21).

Although the nerve may be injured by trauma tothe lateral aspect of the neck, or as a result of tractionforces that reach the nerve because of excessive scapu-lar depression, the most common mechanism ofinjury occurs as a result of surgery within the posteriortriangle of the neck. Examples include biopsy orresection of the lymph node or radical neck dissection.The trapezius alone holds up the lateral point of theshoulder, so dropping of the lateral aspect of theshoulder is one of the most common signs.12,27 Inaddition, shoulder function can be compromisedbecause of the loss of trapezius contribution to scapu-lothoracic elevation and upward rotation.

Thoracic Outlet Syndrome

No discussion of the brachial plexus or its compo-nents is complete without reference to thoracic outletsyndrome. The thoracic outlet syndrome remains ahighly controversial topic in musculoskeletal medicine,with viewpoints that range from skepticism about its


Longthoracicnerve

Pectoralisminor

Serratusanterior

Latissimus

Figure 2-16. The long thoracic nervelies on the superficial aspect of the serra-tus anterior muscle and is responsible forits complete nerve supply.

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existence to elaborate descriptions of its signs and symp-toms. The syndrome is generally considered to arisefrom mechanical compromise to the brachial plexus andassociated vasculature, particularly the subclavian ves-sels. Its wide spectrum of signs and symptoms have vas-cular or neurological characteristics that include anycombination of pain, paresthesias, weakness, vasculardisturbances, sensory loss, and reflex changes related tothe upper extremity. We find that the diagnosis of tho-racic outlet is often vague and in many cases is used as adiagnosis of exclusion when other causes related to suchsigns and symptoms have been ruled out.

Some of the earliest descriptions of neurovascularcompromise in the lateral aspect of the neck weremade in the 1700s when Hunald reported on cases ofneurovascular compromise as a result of an anom-alous rib associated with the last cervical vertebrae.44

Decompression of the neurovascular bundle byremoval of the cervical rib was, and still is, a methodof treatment when the neurovascular bundle appears

to be excessively “arched” over this rib or stretchedover an elongated cervical transverse process. Thiscourse results in traction to the neurovascular bundle.

Since that time, the course that the neurovascularbundle takes from the neck to the axilla has been care-fully studied in order to better understand potentialentrapment sites. The subclavian veins that typicallydrain into the brachiocephalic veins lie on the first ribbetween the anterior scalene and the subclavius mus-cles (Figure 2-22). The right subclavian artery thatbranches off the brachiocephalic artery and the leftsubclavian artery that typically arises from the arch ofthe aorta travel with the lower trunk of the brachialplexus to lie between the anterior and middle scalenemuscles (Figure 2-23). The space through which thesevessels and nerves travel from the neck through theupper lateral chest and into the axilla is referred to asthe thoracic outlet. Several specific anatomical loca-tions within this region can be the sites of mechanicalcompromise (Figure 2-24). These sites include the


Axillaryartery

Longthoracic

nerveFigure 2-17. Traction ofthe long thoracic nerve occurswith scapular retraction anddepression. The most vulner-able part of the nerve is thecomponent between the ser-ratus anterior and lower bor-der of the scalene as it isstretched over the first rib.

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interscalene triangle, or space between the anteriorand middle scalenes; the substance of the musclebellies themselves; over the cervical transverseprocesses; in the costoclavicular space; and the cora-copectoral tunnel, which is found under the pec-toralis minor muscle.

The neurovascular bundle must cross over the topof the first rib. The axons contributing to the forma-tion of the T1 ventral ramus and the lower trunkof the brachial plexus have an especially archedpathway resembling an inverted “U” over the firstrib. During full shoulder elevation, the claviclerotates on its longitudinal axis (see Chapter 4), andtherefore the space between the first rib and the clav-icle is further narrowed.41

It is important to note that various arm and scapulamovements have the potential to alter the architectureof the spaces that the neurovascular bundle traverses.Space occupying conditions such as cervical ribs, bonycallus from old fractures of the clavicle or ribs, andapical lung tumors, or the presence of fibrous bands,can also compromise the plexus and vasculature byaltering the dimensions within the thoracic outlet.

Whereas anatomical variants and congenital anom-alies can result in signs and symptoms of thoracic

outlet syndrome, the majority of nonsurgical presen-tations in the clinic are due to altered mechanics ofthe shoulder girdle or upper back and neck.23

Typically, the age of onset is between 20 and 40, andit is more common in women than men. Poor postureand weak shoulder girdle and scapular muscles oftenaccompany such presentations.

Thoracic outlet syndrome can be classified into twotypes: neurological and vascular.35 Various tests have


Axillarynerve

Posteriorcircumflexhumeralartery

Figure 2-18. The “winging” of the scapula occurswhen the medial border of the scapula loses contact withthe chest wall because of loss of resting muscle tension ofthe serratus anterior.

Figure 2-19. The axillary nerve in the shoulder runsover the posterior and inferior aspect of the shoulderjoint capsule and then emerges from the quadrilateralspace to supply the deltoid and teres minor muscles. Thequadrilateral space is bounded by the teres minor superi-orly, the long head of the triceps medially, the humerallaterally, and the teres major inferiorly. In its coursearound the humerus, the nerve travels with the posteriorhumeral circumflex artery.

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been described that are intended to mechanicallystress the neurovascular bundle or alter the space ittravels in order to reproduce the patient’s symptoms(Figure 2-25). These tests have a high incidence offalse-positive results and therefore cannot be relied onas diagnostic in and of themselves. Objective signssuch as EMG changes, temperature or color changesin the hand that are vascular in nature, or neurologi-cal signs such as muscle weakness, weakness of graspand loss of hand coordination, and reflex changes pro-vide more meaningful information. In addition topain, patients may also complain of paresthesias in theupper extremity, a feeling of heaviness of the arm,arm fatigue, and swelling in the hand.

Nonsurgical management focuses on analysis ofupper quarter mechanics in order to alleviate com-pression to the neurovascular bundle. We prefer touse a program designed to influence the potential

stress points from the neck to the axilla. It includesspecific stretches to the scalene musculature, specificstretches for the pectoralis minor muscle, strengthen-ing of the abdominal mechanism (since the abdomi-nal muscles are primarily responsible for maintainingthe postural relationships of the abdomen, thoraxand shoulder girdle, and cervical spine), and strength-ening of the scapula retractors, scapula upward rota-tors (serratus anterior and trapezius), and theposterior rotator cuff (see Chapter 6).33 It is impor-tant to review sitting and sleeping postures with thepatient in order to design the optimal positions thatwill help to decrease any mechanical stress to the neu-rovascular bundle along its complete course from theneck to the axilla. Also, the patient should be carefullyinstructed in the optimal postural positioning of theshoulder girdle, thorax, and abdomen, in addition tothat of the cervical spine.


Foramenmagnum

Jugularforamen

Sternocleidomastoid

Trapezius

Accessory(XI) nerve

Spinalnucleus

ofaccessory

nerve

Figure 2-20. The spinal accessory nerve originates in the cervical spinal cord and medulla andsupplies motor innervation to the trapezius and sternocleidomastoid muscles.

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Middle scalenemuscle

Anterior scalenemuscle

Subclavius muscle

Subclavian artery

AnteriorscalenemuscleSubclavius

muscle

Subclavianvein

Sternocleido-mastoidmuscle

Accessorynerve

Trapeziusmuscle

Figure 2-21. The spinal accessory nerve travelsthrough the sternocleidomastoid muscle and posteriortriangle of the neck to reach the trapezius muscle. Thisnerve is vulnerable to compression and traction injuriesbecause of its superficial location.

Figure 2-22. The subclavian veins lie on the first ribbetween the anterior scalene and subclavius muscles.

Figure 2-23. The subclavianarteries travel with the lowertrunk of the brachial plexus tolie between the anterior andmiddle scalene muscles.

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12

3

4

12

3

4

Figure 2-24. The thoracic outlet is thespace through which the neurovascularbundle travels and a site of potential nerveentrapment. It is located between the (1)anterior and middle scalenes, at the regionof the (2) cervical transverse process,between the (3) clavicle and first rib, andunder the (4) pectoralis minor muscle.

Figure 2-25. Tests used to assess for tho-racic outlet syndrome are designed tomechanically compromise the neurovascu-lar bundle between the scalene muscles, inthe costoclavicular space, or under the pec-toralis minor. The examiner who under-stands this anatomy can place the arm andshoulder in positions and observe whethervascular or neurological signs can be repro-duced. Always remember that such testshave a high incidence of false-positive andfalse-negative results and therefore will notrender a diagnosis in and of themselves.

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Articular Neurology of the Shoulder

Nerve fibers that supply the joints of the body fol-low Hilton’s law, which states that the nerves to themuscles that act on the joint also supply branches tothe joint itself and the skin over the muscle. Thus theneural supply to the key joints of the shoulder regioninclude (Figure 2-26):

● The glenohumeral joint supplied primarily by theaxillary, musculocutaneous, suprascapular, and sub-scapular nerves

● The acromioclavicular joint supplied by the lateralsupraclavicular nerves that arise from the cervicalplexus and the suprascapular nerve

● The sternoclavicular joint supplied from the medialsupraclavicular nerve branching from the cervicalplexus and the small subclavian nerve that arisesfrom the early part of the brachial plexus

These nerves integrate sensory afferents withmotor efferents. They carry sensory afferents from thejoint and the muscle-tendon units, motor supply tothe extrafusal and intrafusal muscle fibers, and vaso-motor efferents for the vasculature associated with thejoint.

Nociceptive sensory nerve endings are distributedamong the joint capsule and ligaments and recognizepainful sensations that occur when the joint capsule orsupporting ligaments are mechanically or chemicallystressed. These sensory afferents are largely free nerveendings. Ruffini and Pacinian afferents, as well asundifferentiated encapsulated nerve endings, all ofwhich are types of mechanoreceptor sensory nerveendings, have also been found within the gleno-humeral joint capsule and supporting ligaments.45

Whereas the Ruffini endings respond to stretch, thePacinian endings respond to compressive and tensileforces. These peripheral receptors and other encap-sulated mechanoreceptors and free nerve endings areessentially biological transducers that have the uniqueability to convert physical, chemical, and thermalenergy into an action potential in the neuron associ-ated with that particular receptor. The resultingaction potential reaches the CNS, whereupon it pro-duces reflex responses at the spinal cord and brain-stem levels, or conscious awareness of the stimuli atthe cerebral cortex level.19 At the spinal cord levellocal reflexes ensue and the input is further modu-lated through descending cortical or brainstem tracts.Additionally, input from these mechanoreceptors andnociceptors ultimately ascends via multisynaptic

pathways to converge on brainstem nuclei, the cere-bellum, and the cerebral cortex.

Since much of the glenohumeral joint capsule istypically lax in the resting position, very little mechan-ical stress is placed on the mechanoreceptors. Thetightening of specific regions of the capsule and liga-ments that occurs with motion results in deformationof the mechanoreceptors. For example, the inferiorglenohumeral ligament (see Chapter 4) is most laxwith the arm at its side, but in external rotation and inthe high-five position, there is a marked increase in lig-ament tension, which activates the capsular and liga-ment mechanoreceptors. The middle glenohumeralligament becomes taut between 45 and 75 degrees ofexternal rotation, again potentially increasing the acti-vation of the joint mechanoreceptors. Although thereis a wide distribution of mechanoreceptors withinmost of the glenohumeral joint capsular tissues, nomechanoreceptors appear in the glenoid labrum orsubacromial bursa.

The presence of mechanoreceptors in the jointimplies several functions, the most notable of which issynergistic linkage with the musculature of the shoul-der joint and shoulder proprioception. The synergisticconnection between ligaments and musculature wasfirst described in the knee.38,39 This important con-cept has now been extended to the shoulder joint.20

Specifically, reflex arcs are present between themechanoreceptors of the joint capsule and the mus-cles that cross the joint. Shoulder joint stability is thusmore than the passive restraining ability of the spe-cialized connective tissues of the shoulder. Stimulationof the articular mechanoreceptors associated withbranches of the axillary nerve results in immediateand systematic reflex muscle contractions from thesubscapularis, supraspinatus, and infraspinatus mus-cles. Such direct reflex connections between themechanoreceptors of the joint and the cuff musclessuggest a neuromotoric contribution to joint stability.Joint stability is the sum total of the contribution ofthe musculature and the capsular restraints linked tothe nervous system as a result of afferent mechanore-ceptor input and efferent motor output.

In addition to the mechanoreceptors associatedwith the joint capsules and ligaments, a sophisticatedreceptor system is also associated with the muscles andtendons surrounding the joints. Golgi tendon organsand muscle spindles are essential components of themusculature of the shoulder joint.19 It is particularlyrelevant to consider the presence of Golgi tendonorgans, highly sensitive tension receptors located in


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Acromioclavicularjoint

Figure 2-26. Innervation of the glenohumeral joint is supplied primarily by the axillary, musculo-cutaneous, suprascapular, and subscapular nerves. Views A and C show the anterior and posteriorviews of this rich neural supply to the glenohumeral joint and surrounding tissues respectively, whereasview B illustrates the neural supply to the anterior structures, including the acromioclavicular (sup-plied by the lateral supraclavicular nerves that arise from the cervical plexus and the suprascapularnerve) and sternoclavicular joints (supplied by the medial supraclavicular nerve branching from thecervical plexus and the small subclavian nerve arising from the early part of the brachial plexus).

A

C

B

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the rotator cuff tendons, because of the intimate rela-tionship of the tendons to the shoulder joint capsule(see Chapter 4). An intricate feedback mechanismrelaying proprioceptive input from the capsular con-nective tissues to the CNS exists: contraction of therotator cuff muscles stimulates the Golgi tendonorgans and the joint capsule mechanoreceptors, pro-viding immediate feedback on joint activity to theCNS. When you consider the partial thickness rotatorcuff tendon tear (or complete thickness tear) in com-bination with a lax, damaged glenohumeral joint cap-sule, input from the Golgi tendon organs andmechanoreceptors of the joint is diluted and theimportant link between afferent input and efferentoutput is marginal at best.

As noted earlier, this complex of mechanoreceptorslocated within the joint structures themselves, as wellas the surrounding muscles and tendons, is largelyresponsible for communicating proprioceptive infor-mation to all parts of the CNS, including the spinalcord, cerebellum, and cerebral cortex. Proprioceptionincludes the awareness of joint movement (kinesthesiaor rate of movement) and joint position sense (extentof movement). Input from the muscles to the CNS viathe muscle spindles also assists in the analysis of theresistance to movement, and tension within a muscleresults from continuous feedback and feed-forwardloops of afferents and efferents that are associatedwith the muscle spindle.

In addition to these proprioceptive functions, themechanoreceptors are responsible for controlling theresting tension of the muscle and generating reflexresponses.31 Input from the mechanoreceptors ulti-mately affects the state of muscle contraction via influ-ence on the motor neurons responsible for extrafusalmuscle fiber contraction (the skeletal muscle) and intra-fusal muscle fiber contraction (the muscle spindle).

Because the shoulder has such a wide range ofmotion over the different joints and articulations,mechanoreceptors associated with the joint are acti-vated through an extraordinarily wide range, and theCNS is subjected to a barrage of information from thereceptor system. This input converges on the spinalcord, where simple local reflexes, subcortical influ-ences, or cortical override results in the coordinationand synergy between the glenohumeral, scapulotho-racic, and cervical spine muscles.

Later (see Chapters 3 and 4) we will refer to factorsthat contribute to glenohumeral stability. One of themost important but least understood of these factorsis the contribution of the nervous system to shoulder

stability. A continuous interplay between the sensoryafferents coming from the joint capsule and its sup-porting ligaments, muscles, and tendons and themotor efferents of the alpha and gamma motor neu-rons provides for the essential balance of motor activ-ity to allow the joint with the greatest mobility in thebody to simultaneously remain stable. Loss of this keyinterplay may be one of the primary problems withthe unstable glenohumeral joint. The mechanorecep-tors of the capsule are stretch sensitive; thereforelengthened capsular and ligamentous tissue as a resultof injury most likely decreases mechanoreceptorinput to the CNS. Several studies have demonstratedthat patients who have had glenohumeral disloca-tions have proprioceptive deficits, most likely as aresult of capsular and ligamentous damage.25,26,37,43

Conversely, it has been suggested that improved pro-prioception of the glenohumeral joint may occurafter radio frequency assisted thermal capsular shiftin multidirectional instability because of a mechani-cal tightening of lax capsular tissues.10

In essence, it is the unconscious activation of thedynamic stabilizers coupled with the properly timedand synchronized co-activation of musculature associ-ated with the scapulothoracic articulation and theacromioclavicular, sternoclavicular, and glenohumeraljoints that are the essential pieces of rehabilitation formechanical shoulder disorders. While oftentimes arehabilitation plan focuses on restoration of range ofmotion and strength of the shoulder as measured bymaximum weight lifted, torque generated, orendurance as determined by repetitions to failure,these measure only a fraction of total shoulder func-tion. We have previously discussed the concept ofmuscles resembling mechanical springs with varying“set points” of resting tension and the potential ofmuscles’ stiffness (the muscles’ inherent resistance todeformation) contributing to joint stability.32 Thecomparison to mechanical springs allows us to con-sider the benefit of muscle stiffness—the resting ten-sion or turgor of the muscle—and the inherentcontribution to joint stability (Figure 2-27). As demon-strated in the lower extremity, this enhanced state ofmuscle readiness prepares the muscle, and conse-quently the joint, for external loads by heightening thesensitivity of the muscle spindle and quickens thereflexive response of the muscle.8,29b

This neural influence suggests several importantconsiderations in regard to the rehabilitation process.Chapters 3 and 6 describe various resistance exercisesused in training the musculature of the shoulder girdle


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and trunk. Wilk has described the importance of neu-romuscular control of the shoulder complex and itsimportance to the patient in developing and improv-ing neuromotoric control of the shoulder complexduring the rehabilitation process.47,48,49 We agree thatthis aspect of rehabilitation is critical and use severalvariations of such training in the clinical setting tohelp develop neuromuscular control.

One of the first methods used is proprioceptive neu-romuscular facilitation (PNF) technique. This techniqueis more involved than simply moving the extremitythrough a pattern, and three of its aspects are especiallyrelevant to shoulder rehabilitation. These include:

1. Emphasis on the rotary component of the motionregardless of whether the pattern is one of fullrange movement or static holds. This rotary com-ponent is the essential element of the pattern inshoulder rehabilitation when the role of the rotator

cuff and the orientation of the major extrinsicmuscles of the shoulder are understood.

2. Varying the middle segment (elbow motion)regardless of the pattern direction. All too oftenthe diagonal is used with the elbow kept in theextended position. These shoulder patterns are ofneuromotoric value only when the clinician variesthe technique to allow the elbow to move fromflexion to extension or extension to flexion, andnot simply remain in flexion or remain in exten-sion during any pattern direction. Applying thetechnique in this manner begins to more closelyreproduce the sensorimotor demands of theupper extremity in work, sport, and activities ofdaily living. Furthermore, it is an important con-sideration that acknowledges the important rolesthe biceps and triceps play in concert with othershoulder musculature.

3. Proper use of rhythmic stabilization. This techniquerequires the clinician to maintain keen sensoryawareness of the patient’s attempt at movementwithin the pattern. It is far more than simply an iso-metric hold in different ranges. If properly executed,this technique incorporates the essential rotary com-ponent and elbow component and discretely andsubtly alters the rotary or diagonal resistance at dif-ferent points of the range. The clinician can thusposition the joint in weak or vulnerable ranges andbegin the process of gradually challenging theextremity for neuromotoric control.

Another technique to help establish neuromuscularcontrol uses controlled plyometrics. Plyometrics refersto exercises that challenge the neuromuscular systemto produce the maximal force output in the shortestpossible time. The key to a plyometric exercise is thetime it takes for the muscle to reverse from a lengthen-ing phase to a shortening phase. This implies that therate, not the magnitude, of the stretch determines thestorage of elastic energy and the subsequent rapidimplementation of this stored energy into work.

Plyometric exercises endeavor to rapidly storeenergy in the muscles and then dissipate the energy ina manner that allows the elastic properties of the mus-cle to be combined with the active contraction of themuscle. Consequently, this type of training has theadded benefit of enhancing the tolerance and capac-ity of the muscle for increased stretch loads. This isparticularly important for activities in which theglenohumeral joint will be placed in positions vulner-able for subluxation or dislocation.


Anterior

Posterior

Figure 2-27. It is useful to consider muscles as mechan-ical springs with a resting tension associated with thespring. Views A and B show the anterior and posterioraspects of the rotator cuff as springs. An increase in rest-ing muscle tension results in increased capsular tensionand more compression to the joint, both of whichenhance glenohumeral stability.

A

B

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This type of training program requires that the sen-sory system—the stretch to the muscle spindle and theGolgi tendon organs and the stretch or compression tothe mechanoreceptors of the joint—ultimately drivethe resultant desired muscle contraction. Thereforeplyometric exercises are useful for training the sensori-motor system. Many plyometric exercises have beendescribed for the lower extremity (box jumps, squats,bounding). These exercises can also be effective inshoulder rehabilitation if carefully adapted to the spe-cific patient needs. Examples using medicine balls ofvarying weights and circumferences with an emphasison the rate of reversing the muscle action from thelengthening phase to the shortening phase include:

● Medicine ball “presses” from the bench press posi-tion or medicine ball presses from the incline benchposition

● Two-handed soccer throws● Underhand two-handed side throws, single-arm

catch and throws, or push-ups (with knees on floor)to 4-inch block (being very aware of the potentialfor posterior shear at the glenohumeral joint (seeChapter 4)

● Push-ups (with knees on floor) from a 4-inch blockto floor and back up to 4-inch block (again, awareof the posterior shear at the glenohumeral joint)

● Modifications of the plyometric push-ups with thepatient “falling” toward a wall (as in a wall pec-toralis major stretch) and pushing away quickly

● Plyometric sit-ups using elastic energy of musclesinvolved in push pressing activities or plyometric sit-ups using elastic energy from shoulder extensors

The last two exercises offer excellent ways to incor-porate training of the shoulder girdle and abdominalmechanism.

The key to the exercises is that the impact is quicklyabsorbed (fast eccentric phase—stimulus to themechanoreceptors of the joint and the muscle), whichis followed by as “explosive” a contraction as possible(powerful concentric phase—rapid conversion ofsensory input into motor action).

SUMMARY

We have examined several aspects of nervous systemfunction and dysfunction in the shoulder complex. Wedescribed disorders of neural tissue that can give rise tothe perception of shoulder pain, such as nerve rootdisorders, peripheral nerve injuries, and pain referred

from structures outside the shoulder region. In addi-tion, we considered the poorly understood phenome-non of sensorimotor integration over the shoulder.

Very often shoulder pain is analyzed simply on thebasis of a suspected mechanical etiology. The cause ofshoulder dysfunction is much more complex than sim-ply joint laxity of the glenohumeral joint capsule orcompression of the subacromial bursa or rotator cufftendons under the coracoacromial arch. There is anincreased reliance on the precise functioning of theneuromuscular system in meeting both stability andmobility demands because the shoulder joint does nothave exceptional bony stability. The unique interplayof the cervical spine, scapulothoracic articulation, andsternoclavicular, acromioclavicular, and glenohumeraljoints is the result of a continuous interaction betweenafferent and efferent (sensory and motor) neuron loopsthat regulate shoulder function at the reflex, subcorti-cal, and cortical levels. This suggests the importantinfluence of the nervous system for optimal function.An early and safe return to activity after injury is justas important in maintaining CNS health as it is inmaintaining musculoskeletal health. We suggest thatrestoration of function includes integration of theneuromusculoskeletal system, just as it does with thecervical spine, low back, and other peripheral joints.

REFERENCES

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2. Arboleya L, Garcia A: Suprascapular nerve entrapment ofoccupational etiology: clinical and electrophysiological char-acteristics, Clin Exp Rheumatol 11:665, 1993.

3. Asami A, Sonohata M: Bilateral suprascapular nerve entrap-ment syndrome associated with rotator cuff tear, J ShoulderElbow Surg 9:70, 2000.

4. Blom S, Dahlback LO: Nerve injuries in dislocations of the shoul-der joint and fractures of the neck of the humerus: a clinicaland electromyographic study, Acta Chir Scand 136:461, 1970.

5. Bryan WJ, Wild JJ Jr: Isolated infraspinatus atrophy: a commoncause of posterior shoulder pain and weakness in throwingathletes? Am J Sports Med 17:130, 1989.

6. Clancy W, Brand R, Bergfeld J: Upper trunk brachial plexusinjuries in contact sports, Am J Sports Med 5:209, 1977.

7. Cyriax J: Textbook of orthopaedic medicine, vol 1, London, 1978,Bailliere Tindall.

8. DeMont RG, Riemann BL, Ryu KH, et al: The influence offoot position, knee joint angle, and gender on knee musclejoint complex stiffness, J Athl Train 34:115, 1999.

9. DiBenedetto M, Markey K: Electrodiagnostic localization oftraumatic upper trunk brachial plexopathy, Arch Phys MedRehabil 65:15, 1984.

10. Dodenhoff R, Reilly P, Ilk A, et al: Shoulder proprioceptionafter radiofrequency assisted thermal capsular shift.


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Presented at the American Academy of Orthopedics 67thAnnual Meeting, Orlando, Fla, March 2000.

11. Drez D Jr: Suprascapular neuropathy in the differential diag-nosis of rotator cuff injuries, Am J Sports Med 4:43, 1976.

12. Dunn AW: Trapezius paralysis after minor surgical proceduresin the posterior clavicle triangle, South Med J 67:312, 1974.

13. Duralde XA: Neurologic injuries in the athlete’s shoulder,J Athlet Training 3:316, 2000.

14. Dwyer A, April C, Bogduk N: Cervical zygapophyseal joint painpatterns I: a study of normal volunteers, Spine 15:453, 1990.

15. Gardner E: The innervation of the shoulder joint, Anat Rec102:1, 1948.

16. Goodman CE, Kenrick MM, Blum MV: Long thoracic nervepalsy: a follow-up study, Arch Phys Med Rehabil 56:352, 1975.

17. Gregg JR, Lobosky D, Harty M, et al: Serratus anterior paral-ysis in the young athlete, J Bone Joint Surg Am 61:825, 1979.

18. Grieve G: Referred pain. In Grieve G, editor: Modern manualtherapy of the vertebral column. Edinburgh, 1986, ChurchillLivingstone.

19. Grigg P: Peripheral neural mechanism in proprioception,J Sports Rehabil 3:2, 1994.

20. Guanche C, Knatt T, Solomonow M, et al: The synergisticaction of the capsule and shoulder muscles, Am J Sports Med23:301, 1995.

21. Hester P, David N, Caborn M, et al: Cause of long thoracicnerve palsy: a possible dynamic fascial sling cause, J ShoulderElbow Surg 9(1):31, 2000.

22. Hirasawa Y: Injuries to peripheral nerve in sport, Semin Orthop3:240, 1988.

23. Karas SE: Thoracic outlet syndrome, Clin Sports Med 9:297,1990.

24. Katzman BM, Bozentka DJ: Peripheral nerve injuries second-ary to missiles, Hand Clin 15:233, 1999.

25. Lephart SM, Henry TJ: The physiological basis for open andclosed kinetic chain rehabilitation for the upper extremity,J Sport Rehabil 5:71, 1996.

26. Lephart SM, Warner JP, Borsa PA, et al: Proprioception of theshoulder joint in healthy, unstable, and surgically repairedshoulders, J Shoulder Elbow Surg 3(6):371, 1994.

27. Logigian EL, McInnes JM, Berger AR, et al: Stretch inducedspinal accessory nerve palsy, Muscle Nerve 2:146, 1988.

28. Loomer R, Graham B: Anatomy of the axillary nerve and its rela-tion to the inferior capsular shift, Clin Orthop 243:100, 1989.

29a.Matsen FA, Thomas SC, Rockwood CS, et al: Glenohumeralinstability. In Rockwood CA, Matsen FA, editors: TheShoulder, ed 2, Philadelphia, 1998, WB Saunders.

29b.McNair PJ, Wood GA, Marshall RN: Stiffness of the hamstringmuscles and its relationship to function in anterior cruciatedeficient individuals, Clin Biomech 7:131, 1992.

30. Mestdagh M, Drizenko A, Ghestem P: Anatomical basis ofsuprascapular nerve syndrome, Anat Clin 3:67, 1981.

31. Michelson JD, Hutchins C: Mechanoreceptors in human ankleligaments, J Bone Joint Surg Am 77(2):219, 1995.


33. Porterfield JA, DeRosa C: Mechanical neck pain: perspectives in func-tional anatomy, Philadelphia, 1995, WB Saunders.

34. Rengachary SS, Burr D, Lucas S, et al: Suprascapular nerveentrapment neuropathy: a clinical, anatomical, and compar-ative study, part II, Neurosurgery 5:447, 1979.

35. Royan G: Thoracic outlet syndrome, J Shoulder Elbow Surg7:440, 1988.

36. Sicuranza MJ, McCue FC III: Compressive neuropathies in theupper extremity of athletes, Hand Clin 8:263, 1992.

37. Smith RH, Brunolti J: Shoulder kinesthesia after anteriorglenohumeral joint dislocation, Phys Ther 69:106, 1989.

38. Solomonow M, Baratta R, Zhou BH, et al: The synergisticaction of the anterior cruciate ligament and thigh muscles inmaintaining joint stability, Am J Sports Med 15:207, 1987.

39. Solomonow M, D’Ambrosia RD: Neural reflex arcs and mus-cle control of knee stability and motion. In Scott WN, editor:The knee, St. Louis, 1994, Mosby.

40. Solomonow M, Guanche C, Wink C, et al: Mechanoreceptorsand reflex arc in the feline shoulder, J Shoulder Elbow Surg5:139, 1996.

41. Telford E, Mottershead S: Pressure at the cervical brachialjunction: an operative and anatomical study, J Bone Joint Surg(Br) 30B:249, 1948.

42. Thompson RC Jr, Schneider W, Kennedy T: Entrapment neu-ropathy of the inferior branch of the suprascapular nerve byganglia, Clin Orthop 166:185, 1982.

43. Tibone JE, Fletcher J, Kao JT: Evaluation of a proprioceptionpathway in patients with stable and unstable shoulders withsomatosensory cortical evoked potentials, J Shoulder ElbowSurg 6:440, 1997.

44. Tyson RR, Kaplan GF: Modern concepts of diagnosis andtreatment of the thoracic outlet syndrome, Orthop Clin NorthAm 6:507, 1975.

45. Vangsness CT Jr, Ennis M, Taylor JG, et al: Neural anatomy ofthe glenohumeral ligaments, labrum, and subacromial bursa,Arthroscopy 11:180, 1995.

46. Vastamaki M, Kauppila LI: Etiological factors in isolated paral-ysis of the serratus anterior muscle: a report of 197 cases,J Shoulder Elbow Surg 2:240, 1993.

47. Wilk KE, Arrigo CA: An integrated approach to upper extrem-ity exercises, Orthop Phys Ther Clin North Am 9:337, 1992.

48. Wilk KE, Arrigo CA: Current concepts in the rehabilitationof the athletic shoulder, J Orthop Sports Phys Ther 18:365,1993.

49. Wilk KE, Arrigo CA, Andrews JR: Current concepts: the stabi-lizing structures of the glenohumeral joint, J Orthop SportsPhys Ther 25(6):364, 1997.


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INTRODUCTION

The highly mobile shoulder complex represents amarvelous and fairly unique example of the way inwhich multiple joints and articulations are preciselycontrolled by extremely diverse musculature via thecentral and peripheral nervous systems. WhereasChapter 2 reviewed the pertinent afferent and efferentneurology of the system and Chapter 4 will detail jointstructure and function of the articulations, this chap-ter provides us with the framework needed to examinethe roles that individual muscles and groups of mus-cles play in meeting the simultaneous demands of sta-bility and mobility.

The purpose of this chapter is to assist you in gain-ing a three-dimensional understanding of the shouldergirdle musculature. This knowledge, when coupled withan understanding of glenohumeral, scapulothoracic,and trunk mechanics, provides the basis for the evalua-tion and treatment of shoulder disorders. The synergis-tic interplay among muscles, tendons, capsules, fascia,and bone gives us the ability to move in a coordinated

manner. This interplay is readily apparent in a study ofthe shoulder, which, not being a weight-bearing joint,relies heavily on the spine, trunk, and even the lowerextremities to create a stable yet immediately adaptableplatform from which to function. The scapulothoracicarticulation in particular must quickly get into positionto serve as a platform for glenohumeral motion. Suchinterrelationships between different regions of the mus-culoskeletal system is unparalleled in the human bodyand speaks to the complexity of analyzing shoulder dis-orders and then addressing them in as holistic a manneras possible. Throughout this chapter, identification ofanatomical and mechanical linkages between individ-ual muscles of the shoulder girdle and between thetrunk and shoulder girdle is illustrated and discussedwith the intent being to assist the clinician in the deci-sion making processes associated with the analysis ofnormal and abnormal function.

We also examine muscle structure here as it relates toshoulder girdle functions and carefully consider theinterconnections and mechanical linkages between dif-ferent muscles. This allows us to better determine therelationship of muscle structure to function. Clinicallyapplicable observations and suggestions are includedthroughout the chapter to assist you in understandinginterrelationships between the anatomy and biomechan-ics as a foundation for use in solving problems ofmechanical disorders related to the shoulder girdle com-plex. When muscle structure is reviewed in this manner,

CHAPTER 3Rhomboid minor/major

Supraspinatus

Infraspinatus

Teres minor

Serratusanterior

MUSCULATURE OF THESHOULDER COMPLEX

47

Throughout this chapter you will find small circular icons marked“DVD” (see margin). These icons identify content that is coordi-nated with a video clip on the DVD accompanying this text. Formaximum learning benefit, go to the “Text Reference Section” onthe DVD and play the coordinated clip while reading the appropri-ate section of text. These clips expand on and reinforce the infor-mation presented in the text.

DVD

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the importance of maintaining muscular mass andstrength in order to ensure coordinated movement andpainless performance becomes increasingly apparent.

MUSCLE STRUCTURE

Among the many characteristics of muscle, thereare four that are important to consider when studyingits function and relationship to force transmission:structure, attachment considerations, relationship ofthe muscle to the joint, and crossing relationshipsbetween different muscles (Table 3-1). Each character-istic in turn has important clinical implications. Thefirst characteristic is the structure of the muscle. Thisincludes not only the cross-sectional area of the mus-cle, but also the relationship of the muscle fiber to thetendinous attachment. Typically, the physiologicalcross section of a muscle is directly related to its ten-sion generating ability. In most instances, the largerthe cross-sectional area of the muscle, the greater abil-ity it has to generate force. Increases in the cross-sectional area of skeletal muscle via strength trainingis a biological adaptation resulting from increasedworkload placed on the muscle, which is an importantprinciple to understand when developing exercise pro-grams. Overload is the essential ingredient for influ-encing increased hypertrophic changes in the muscle.

The adaptation of increased muscle size leads to anincrease in the muscle’s capacity to generate tension.Muscle hypertrophy in response to overload trainingoccurs primarily as a result of the enlargement ofindividual muscle fibers. This process of hypertrophyis directly related to the synthesis of cellular matrix,which is primarily protein and forms the contractileelements.13 It is important to remember, however, thatincreases in strength, as they are typically measured ina clinical or laboratory environment, also occur as aresult of neurological changes (e.g., alteration ofinhibitory and facilitatory pathways) and psychologi-cal influences.

The force of a muscle contraction from a muscle

with an oblique or spiral orientation can be resolvedinto several component vectors in addition to a forceparallel to that muscle’s tendon. Note, for example, thedifferent structural arrangement of the levator scapu-lae (a spiral arrangement of fibers), the infraspinatus(three heads converging centrally in a tendon andencased in a fascial envelope), and the deltoid muscle(three heads converging distally in a tendon). Whenviewed in this manner, you can begin to appreciatethat muscle function over a complex region such as theshoulder is more than merely moving the insertiontoward the origin. What appears to be a simple con-traction of a muscle results in unique consequences tothe various tissues the muscle interfaces with. A clini-cian explores several of these examples when heexamines individual muscles of the shoulder. Nearlyevery muscle in the shoulder girdle has a unique struc-ture and muscle fiber orientation, suggesting a uniquecontribution to the wide scope of motion potentialover a platform of stability.

The range of muscle contraction is dependent onmuscle fiber length. Simply put, a muscle with longmuscle fibers is designed for speed or excursion. Thisdoes not necessarily mean that a joint moves “faster”because it has muscles with long fibers associated withit. The point at which the muscle attaches to the bonylever and the manner in which the muscle-tendon unitapproaches the attachment ultimately determine thespeed at which the articulation moves, which is a muchdifferent concept than the speed at which a muscleshortens. Again, you see that the relationship betweenthe muscle and its tendinous endpoints helps deter-mine this range of contraction. Longitudinally ori-ented muscle fiber arrangements generate rapidmuscle shortening or speed, whereas obliquely ori-ented muscle fibers, such as those arrangements thatoccur with unipennate, bipennate, or multipennatepatterns, permit more muscle cells to be included in thesame volume, resulting in greater tension generatingability but less potential for extensive excursions of thebony levers. The potential force of muscle contractionand the resultant range of motion are thus markedlyinfluenced by the fiber arrangement.

Tendinous Attachment to Bone

A second consideration that influences muscle func-tion relates to the type of tendinous attachment of themuscle to the bony levers, such as the humerus, scapula,and clavicle. Several muscles of the shoulder girdle,

48 MUSCULATURE OF THE SHOULDER COMPLEX

Table 3-1. Characteristics of MuscleInfluencing Function

1. Structure of the muscle2. Attachment of the muscle to the bony lever3. Relationship of the muscle to the joint structure4. Crossing relationships of muscles

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including the supraspinatus, infraspinatus, and teresminor, blend together to form a conjoint tendon,whereas other muscles, such as the long head of thebiceps brachii, direct their effect to the labrum via a sin-gle robust tendon. Still others have a twisting or spiralcourse as the muscle links the two bony ends. In severalkey muscles of the shoulder complex, there is a twistingand spiral course. These muscles include the intricatetrilaminar fiber arrangement of the pectoralis majortendon, the latissimus dorsi tendon, the muscle fibers ofthe levator scapulae, and the weaving of the muscle fibersof the infraspinatus. No muscle acts in isolation. Rather, acoordinated series of muscle contractions creates loadson all tissues in the region throughout the range ofmovement. Simply stated, the continuum of load trans-ference between tissues results from muscle contraction.

Anatomical Relationship of Muscleto Joint

In addition to the cross-sectional area of the mus-cle, the fiber arrangement and orientation of themuscle fibers as well as the location of the tendonattachment in relation to the bony lever, influence thetypes of loads to which the articulations are subject. Thedifferences in muscle fiber arrangement and tendinousattachments ultimately allow for a wider range of possi-bilities regarding the line of pull of the muscle, the speedof bony lever movement, the muscle tension generatedover the related articulation, and the compressionbetween the joint surfaces. Thus the third biomechani-cal and physiological consideration for each muscle isthe relationship that the contractile unit has to the jointstructures. When muscles act to stabilize and move thearm, they generate forces that must be weakened by thespecialized connective tissues of the joint. These forcesare generally torque, compression, and shear.

Torque is the force that drives one of the bonylevers around an axis of motion, resulting in an arc ofmotion by the bony lever. This arc of motion is typicalfor the synovial joints of the body. Since the bony leveris moving around an axis, the distance the muscleattaches from this axis (the moment arm) determinesnot only the speed at which the articulation moves, butalso the relative efficiency of the muscle acting to gen-erate torque over that particular joint. Torque isimportant to understand because the closer that amuscle attaches to the axis of motion, the greaterpotential range of motion for the bony levers. Thiscomes with an expense, however, of having a less than

optimal mechanical advantage. Conversely, if a mus-cle is attached at a significant distance from the axis ofmotion, it has an excellent mechanical advantage tocontribute to torque generation, but the speed atwhich the bony levers move is lessened.

It is also important to remember that the axis ofmotion is not fixed, but changes as movement occurs.This is one of the difficulties in using resistance exer-cise machines, which essentially have a fixed axis ofmotion. Such machines are commonly used whenstrengthening interventions are applied to the shoul-der. Selectorized weight machines for muscles associ-ated with the shoulder girdle, such as the lateralshoulder raise, incline press, overhead press, shoulderdip, elbow curl, and elbow extension machines, forexample, have a fixed axis of movement, which unfor-tunately cannot be instantaneously aligned with themoving axes of the shoulder girdle during the exercise.When you align the axis of the glenohumeral jointwith such an exercise machine to start the exercise, theinstantaneous axis of motion for the glenohumeraljoint assumes different positions as the bony leversmove through a range, which results in misalignmentbetween the axis of the glenohumeral joint and theaxis of the exercise unit.

The articulations are also subjected to compressiveloads as the muscle contracts. Compression as it mightrelate to joint structure refers to a force that is directedtoward the center of the joint or perpendicular to theplane of the joint surface. Compressive loads can con-tribute to joint stability over the various articulationsof the shoulder complex because such forces help seatthe humeral head into the glenoid socket or squeezethe bones of the acromioclavicular or sternoclavicularjoint together, resulting in increased joint stability.

Muscle contraction can also result in compressionto subjacent tissues. When a muscle contracts, itbroadens, and the broadening effect can load anunderlying tissue in compression. For example, con-traction of the serratus anterior muscle exerts a com-pressive force to the underlying subscapular bursa.Contraction of the latissimus dorsi muscle as it crossesthe inferior corner of the scapula “presses” thescapula against the rib cage, which results in increasedscapulothoracic stability.

Shear forces are those forces parallel to the referencejoint surface that can result in a translation or slidingof one bone on the joint surface. Shear forces chal-lenge the specialized connective tissues of the synovialjoint because shear results in frictional loading, whichcan contribute to erosion of the two joint surfaces that

MUSCULATURE OF THE SHOULDER COMPLEX 49

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are in contact with each other. This is the case with thesuperior surface of the rotator cuff tendons under thecoracoacromial arch, the humeral head over the gle-noid labrum, or the undersurface (articular surface) ofthe supraspinatus tendon over the posterosuperioraspect of the glenoid rim.12,42

The line of force of muscle contraction can oftenbe resolved into component forces, which can thenbe analyzed to understand their effects over the jointstructures (Figure 3-1). The combination of musclecontractions about the joint generates the sum totalof forces, which ultimately determines the manner inwhich associated structures are stressed. Uncoordi-nated muscle action and muscle fatigue alter theloading pattern of the tissues. This is problematic ifsuch loads exceed the physiological loading capacityof the tissue (see Chapter 1). For example, in thepresence of damaged anterior glenohumeral liga-ments, contraction of the pectoralis major can resultin excessive anterior translation of the humeral headover the glenoid rim.

Crossing Relationshipof Overlapping Muscles

Finally, an important anatomical arrangement ofthe shoulder girdle musculature that we describe anddiscuss throughout this chapter is the overlapping or

crossing relationships of muscles that are in immedi-ate proximity to each other, often with muscle fiberorientations being 90 degrees perpendicular to eachother (Table 3-2). Our premise is that the crossingrelationship increases stability and strength in thatspecific region, especially in regard to the develop-ment of the exercise prescription for rehabilitation,and therefore should represent the focus ofstrengthening exercises. This suggestion, which wecouple with exploring the anatomical and biome-chanical relationships between the shoulder girdleand the trunk, constitutes the essential focus in thedevelopment of strength training interventions. Thisconcept is continually referred to throughout thischapter.

We describe the pertinent characteristics of struc-ture, function, and clinical biomechanics for eachmuscle in this chapter. This review of the musculatureallows you to gain different perspectives of the func-tional anatomy of the shoulder complex, which wewill apply in the design of practical examinationmethods that lead to the implementation of successfulinterventions.

We group muscles and their relationships to sur-rounding structures in six sections: 1) superficialmusculature, 2) scapular layer, 3) posterior scapularlayer, 4) subscapular region, 5) anterior shoulder,and 6) abdominal musculature. A short list of repre-sentative exercises is included with each section toreinforce some of the actions that are inherent in thedifferent muscles described therein. Chapter 6focuses on the setup and technique for such exer-cises, as well as how they might be incorporated intothe scheme of rehabilitation for mechanical shoul-der disorders.


Muscle pull

Inferiorshear

Joint compression

Figure 3-1. The resultant force is a single force that isthe combination or sum effect of all forces directed to ajoint structure. Here we see the resultant force at theglenohumeral joint at 45 degrees of abduction.

Table 3-2. Crossing Arrangements inMuscles of the Shoulder Complex

1. Latissimus dorsi and serratus anterior, posterior and lateral2. Latissimus dorsi and gluteus maximus, posterior and central3. Serratus anterior across the abdominal wall bilaterally

(serape effect), anterior and central4. Trapezius and rhomboids, posterior and superior5. Pectoralis major bilaterally, anterior and superior6. Long head of the triceps and the teres major across the

infraspinatus, posterior glenohumeral joint7. Coracobrachialis across the short head of the biceps

brachii and the subscapularis, anterior glenohumeral joint

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THE SUPERFICIALMUSCULATURE

Three muscles are discussed in this section: 1) thelatissimus dorsi, 2) the teres major, and 3) the trapez-ius. During dissection, the latissimus dorsi and trapeziusmuscles are readily seen on removal of the skin andsuperficial fat, whereas the teres major, althoughsuperficial, is not as immediately apparent. The super-ficial nature of each of these muscles can easily beappreciated in the living body through direct palpa-tion and observation of muscle lines during activity.

Latissimus Dorsi

The latissimus dorsi is a large and powerful extrin-sic muscle of the shoulder girdle and superficial layerof the back that contributes to the stability of thelower thoracic and lumbar spine and has essentialroles in the function of the scapula and the gleno-humeral joint. It is an extensive, broad, fan-shapedmuscle that exerts several distinct lines of force: infe-rior and medial in relationship to the humerus, andsuperior and lateral through the thoracolumbar fasciarelative to the lumbar spine and iliac crest. From itsextensive attachment to the iliac crest, thoracolumbarfascia, and thoracic spinous processes, the musclecourses toward the medial lip of the bicipital groove,and as it approaches the humerus, the muscle tendoncomplex spirals on itself approximately 180 degrees(Figure 3-2). Here it blends with the teres major at itsinsertion on the humerus and controls humeralmotion directly and shoulder girdle motion indirectlyfrom several different vantage points: the pelvis, thethoracolumbar fascia, and the thoracic spine.

In addition, the course and attachments of the latis-simus dorsi allow it to control the position and motionof the scapula because of its superficial position to theinferior border of the scapula. Contraction of thelatissimus dorsi results in compression of the scapulaon the rib cage.

When the superior border of the latissimus dorsimuscle is lifted away from the rib cage, you can alsoview the mechanical linkage it has with the serratusanterior muscle. Figure 3-3, A and B, demonstratesan inferior attachment of the serratus anterior to theundersurface of the latissimus dorsi. Analyzing theresultant forces of these two muscles suggests thatthe latissimus dorsi is pulled against the rib cage andover the inferior border of the scapula as a result of


Figure 3-2. Observe the line of attachment of the latis-simus dorsi muscle from the medial lip of the intertuber-cular groove of the humerus to the thoracic spinousprocesses (horizontal force line), to the thoracolumbarfascia (oblique force line), and to the iliac crest (verticalforce line). Note how this muscle courses inferiorly, thenpasses under the lower trapezius to reach the spinousprocesses of the thoracic vertebrae, and finally fans outobliquely to attach to the thoracolumbar fascia and iliaccrest to cover the entire posterior aspect to the trunk.

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serratus anterior muscle contraction. This con-tributes to forming a semirigid attachment fromwhich the serratus anterior can pull, and such amechanism also keeps the scapula compressedagainst the rib cage.

The action of the latissimus dorsi over the humerusis very powerful. It is a strong adductor, extensor, andinternal rotator of the humerus. As a result, the latis-simus dorsi is a key muscle in the acceleration phase ofthrowing. The acceleration phase, common in manyoverhead sports, is considered the phase of throwingduring which the arm is propelled forward and a pow-erful internal rotation motion occurs.20 Note that thismovement is also prevalent with overhead tennis servesand volleyball spikes. The line of force of the musclealso suggests that the glenohumeral joint has an infe-rior shear force imparted to it as a result of the latis-simus muscle contraction. Acting through theglenohumeral joint, the latissimus dorsi depresses andslightly retracts the scapulothoracic articulation, whichresults in an inferior shear force at the acromioclavicu-lar joint and downward rotation at the sternoclavicularjoint. Like most muscles in the neuromuscular system,the latissimus dorsi generates its greatest force closer tothe midrange position, as seen when the arms are in aflexed and abducted position.1 This muscle is especiallystrong in diagonal motions such as adduction towardthe body and adduction and internal rotation, a com-mon component of the proprioceptive neuromuscularfacilitation (PNF) diagonal.7

There are several crossing relationships amongmuscles of the shoulder girdle complex that areimportant to recognize (see Table 3-2). The first is thelatissimus dorsi’s crossing relationship with the gluteusmaximus muscle via the thoracolumbar fascia. Thelatissimus dorsi tightens or pulls this fascia in a supe-rior and lateral direction. The line of force of the rightlatissimus dorsi, in conjunction with the inferior andlateral pull on the contralateral side of the thora-columbar fascia via the left gluteus maximus, formsone line of an X. The latissimus dorsi and gluteusmaximus of the contralateral side form a second lineof the X (Figure 3-4). These four lines of pull intersectover the lumbar spine, providing force generation thatcrosses the midline. The crossing of these lines offorce represents an area of required strength andtherefore should represent a focus of exercise pre-scription in the development of therapeutic exerciseinterventions.

You can best understand the second crossing rela-tionship involving the latissimus dorsi by viewing themusculature in the sagittal plane from humerus to iliaccrest (Figure 3-5). From this vantage point the musclecan be seen to connect the shoulder girdle to the pelvisand form one arm of an X, with the serratus anteriorforming the second arm of this X. This muscle


Latissimus dorsi

Serratus anteriorRight scapula(inferior border)

BFigure 3-3. A and B, The superior view of the rightlatissimus dorsi has been lifted off the rib cage to showits linkage to the serratus anterior muscle. This mechan-ical linkage suggests one muscle working with another toimprove its mechanical advantage. Contraction of theserratus anterior pulls the latissimus against the rib cageand the inferior border of the scapula.

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crossing is formed as a result of the latissimus dorsitraveling from its attachment on the humerus in aninferior and posterior direction and the serratus ante-rior traveling from its attachment on the undersurfaceof the scapula in an inferior and anterior direction (seeFigure 3-5). Again, analyzing the actions of musclesthat overlap in perpendicular directions forms thebasis for understanding the role of musculature inantigravity postures and the importance of strengthfor muscle groups contributing to such arrangements.

Teres Major

Even though they arise from different regions, sev-eral of the actions of the teres major and latissimusdorsi over the glenohumeral joint are similar becauseof their nearly blended attachments to the humerus.The teres major arises from the middle third of thelateral surface of the scapula and the intermuscularsepta that separates the teres major from the teresminor and courses laterally by spiraling upward to endas a flat tendon that attaches to the medial lip of the


Figure 3-4. The latissimus dorsi and gluteus max-imus attachment to the thoracolumbar fascia illustratestheir crossing lines of force. This crossing relationshipof the muscles suggests the importance of focusing anexercise program to target this and similar regions.

Figure 3-5. This sagittal view shows the relationshipbetween the inferior and posterior direction of the latis-simus dorsi and the inferior and anterior direction of theserratus anterior. The focus of therapeutic exercise mustbe at the point where these opposite vectors cross.

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bicipital groove. The tendons of the large teres majorand latissimus dorsi muscles typically intersect, whichresults in the teres major lying just posterior to thelatissimus dorsi at the bicipital groove (Figure 3-6).The tendons of these two muscles are separated by abursa, and their muscle bellies can be seen to unite fora short period if they are followed proximally fromtheir attachments to the humerus.

The teres major is a stout, thick fusiform muscle,implying exceptional tension generating ability andstrength potential. The actions of the teres majorover the humerus are adduction, extension, and inter-nal rotation, and like those of the latissimus dorsi areemphasized in the combined diagonal motion in PNFpatterns.

Note, however, that the scapula must be effectivelyfixed in order for the teres major to transmit the forceof muscle contraction to the humerus. Exercises for the

teres major by definition require a strong, synchronouscontraction of scapular muscles such as the rhomboidsand trapezius that serves to fix the medial border of thescapula and prevent it from being pulled laterally bythe contraction of the teres major. Always keep this inmind when performing a shoulder adduction muscletest on a patient. Weakness may not be due to animpairment of the teres major but instead may arisebecause of an inability of the scapular muscle to createa stable platform from which the teres major can pull.

The spiraling structure of muscle is one in whichthe inferiormost aspect of muscle twists on itselfenroute to its opposite attachment. What was the low-est point of the muscle at the region of its “origin”becomes the highest point at the region of the “inser-tion,” or what was originally posterior now faces ante-rior. The teres major attachment on the lower aspectof the scapula becomes the superior attachment onthe humerus. This spiral structure of muscle is seen inseveral other areas of the body, namely the teres majorand latissimus dorsi on the posterior shoulder, the pec-toralis major on the anterior shoulder, the levatorscapulae at the medial aspect of the scapula and cer-vical spine, the distal end of the biceps brachii, thedeep erector spinae of the low back, and the ham-strings. Each of us can also see similar spiral structuralarrangements applied to the steel cables used in sus-pension bridges and in the twisting of the strands ofrope. The spiral nature of such structures increasestheir ability to reduce tension because as tensilestresses are imparted to a spiral structure, the tensileload also is attenuated via increased compressive load-ing between the spiraled fibers. The individual fibersof the muscle or steel in the twisted cables “squeeze”together when the ends are pulled apart. A spiralstructure withstands greater tensile loads because it isdissipating the force via compression and the fibersbecome more packed together the greater the tensileforce. Spiraling creates an increased potential for tis-sue strength. Muscles such as the teres major, latis-simus dorsi, and pectoralis major are very strongbecause of their cross-sectional area, as well as thisunique fiber orientation.

Exercises designed to strengthen the different mus-cle groups are listed in Table 3-3 as a point of refer-ence so you can begin to visualize them. Note thatmany of the exercises for the teres major are also onesthat can be effectively used in the training of the latis-simus dorsi.

Discussion in Chapter 6 focuses on exercise trainingdescriptions, illustrations, and prescriptions.


Teresmajor

Latissimusdorsi

Latissimusdorsi

Figure 3-6. The teres major muscle spirals or twists asit travels superiorly and laterally from the middle third ofthe lateral border of the scapula. It briefly unites with thelatissimus dorsi muscle, and the two course superiorlyand laterally toward their attachment. These muscleseventually split to form separate tendons. The flat tendonof the teres major attaches to the medial lip of the bicip-ital groove just posterior to the latissimus dorsi. Althoughtheir innervations are different, their functions at thehumerus are similar.

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Trapezius

The final muscle to be described in this superficiallayer is the trapezius muscle. This large, expansive mus-cle with its superior, middle, and inferior heads coversthe upper back and has at its center a diamond-shapedtendinous tissue often referred to as the trapezius aponeu-rosis. The connective tissue of this thick aponeurosisaffords strength at the important cervicothoracic junc-tion and acts as the base for the strong superior, hori-zontal, and inferior pull of the muscle. The shape ofthis aponeurosis also suggests that one of this muscle’smain functions is to assist in the maintenance of aretracted position of the scapula (Figure 3-7).

Close examination of all three portions of thisexpansive muscle suggests that each region has differ-ent fiber orientation and that the varying thickness ofthe muscle points to histological differences. Thelower portion of the trapezius that courses from thethoracic spinous processes to the medial border of thescapula appears to be composed primarily of Type I


Upper

Aponeurosis

Middle

Lower

Table 3-3. Exercises for the SuperficialMusculature

Latissimus and Teres Major

Wide angled pulldownsOne-armed bench rowsSeated cable rowsBent over rowsStanding high cable rowsSeated dips (scapular depression)Counter weighted dips and pull-upsPNF diagonals (extension, adduction, internal rotation)

against pulleys

Trapezius

ShrugsShrug with pre-positioning humerus in external rotationSeated rows emphasizing scapular motion in retractionStanding high and mid row emphasizing scapular motion in

elevation and retractionOne-arm rowsHorizontal adduction on selectorized machinesBilateral pulley horizontal adductions

Figure 3-7. The three heads of the trapezius muscle show its central tendinous aponeurosis. Thedifferences in structure between the upper, middle, and lower portions of the trapezius can also beappreciated. The position of the aponeurosis suggests that it serves as the foundation for the back-ward directed pull of the trapezius, helping to keep the scapula back toward retraction. (FromPorterfield JA, DeRosa C: Mechanical neck pain: perspectives in functional anatomy, Philadelphia, 1994,WB Saunders.)

*PNF, Proprioceptive neuromuscular facilitation.

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fibers, whereas the upper portion reaching from theocciput to the lateral portion of the clavicle has ahigher percentage of Type II fibers.24,25 This may sug-gest that the lower portion of the trapezius is primarilyinvolved with the maintenance of a stable scapularplatform rather than being the primary muscle forceresponsible for the generation of torque to thescapula.21 By comparison, upper trapezius function isprimarily the generation of more dynamic, explosive,or rapid movements.

If the upper portion of the trapezius reaches theocciput (occasionally it does not), it is attached by a thin,fibrous lamina to the medial third of the superiornuchal line. Over the cervical spine it is attached to theligamentum nuchae and the spinous processes.52 Thesemuscle fibers typically angle inferiorly, laterally, andanteriorly to reach the lateral third of the clavicle, the

acromion, and the spine of the scapula. This directlycorresponds to the same bony areas from which the del-toid muscle originates. The primary actions of this por-tion of the upper trapezius muscle are scapularelevation and strong retraction. In order for the trape-zius to exert its force over the scapula, the cervical spinemust be stabilized by the anterior neck flexors to allowa fixed point of origin (Figure 3-8). By virtue of its cla-vicular and acromion attachment, the upper trapezius,like the anterior deltoid, is an extremely important sta-bilizer of the acromioclavicular joint because thesemuscles completely span the joint.26,50 The uppertrapezius muscle attachment allows the upper trapeziusto literally serve as a dynamic suspensory “cable” for theupper extremity.

The middle trapezius is a much thicker portion ofthe muscle when compared with the upper trapezius.


Vector ofanteriormuscles

Uppertrapezius

Figure 3-8. The upper trapezius muscletravels inferiorly, laterally, and anteriorly toattach to the lateral aspect of the clavicle,acromion, and the spine of the scapula, but toexert its force over the scapula, the cervicalspine must be stabilized by the anterior mus-cles of the neck. (From Porterfield JA, DeRosaC: Mechanical neck pain: perspectives in functionalanatomy, Philadelphia, 1994, WB Saunders.)

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The fibers are laced with connective tissue as it courseslaterally from the spinous processes and the middleportion of the trapezius aponeurosis toward the spineof the scapula. Because of the inclination of the spine ofthe scapula, the direction of pull is not oriented paral-lel to the spine of the scapula. This is an importantpoint to remember when visualizing the scapula mov-ing or fixated in varying degrees of upward or down-ward rotation.

The coarse structure and the thick tendinous inser-tion at the spine of the scapula and at its attachmentinto the thickest portion of the aponeurosis suggeststrength and the importance of maintaining scapularretraction. There is a direct relationship between theforces at the glenohumeral joint, the forces atsuprahumeral space, and the position of the

scapula.19,41 Increasing and maintaining strength,power, and endurance in this part of the upper backis paramount to painless function and enhanced per-formance of the shoulder girdle. Learning to movethe scapula irrespective of the humerus and visualiz-ing the direction of muscle pull represent key consid-erations in training the shoulder complex.

The lower portion of the trapezius is a long, thickmuscle, traveling inferior and medial from the spine ofthe scapula and the fascia covering the infraspinatusmuscle to the thoracic spinous processes (Figure 3-9).Because of the similarity of angles in the anatomicalposition, the muscle fiber orientation of the lowerportion of the trapezius and the spine of the scapulaforms a nearly continuous line that begins at theacromion and terminates in the lower thoracicspine. The attachment of the trapezius to the spineof the scapulae is very tendinous, which suggests theconvergence of significant forces. You can appreci-ate this by viewing the deep surface of the lowertrapezius as it is reflected superiorly (Figure 3-10).

Keeping in mind that no muscle works in isolationand that any motion of the scapula requires synergisticmuscle activity to stabilize the occiput, cervical spine,


Trapezius(undersurface)

Rhomboid X

Figure 3-9. The attachments of the lower trapeziusshow how the muscle is also attached to the superficialsurface of the infraspinatus fascia.

Figure 3-10. Note the deep surface of the trapezius inthis photograph of the thick tendinous attachments ofthe lower trapezius to the spine of the scapula (markedby the X).

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and thoracic spine, you will understand that the upperfibers of the trapezius assist with elevation of the shoul-der girdle, the middle fibers assist with retraction, andthe lower trapezius assists with depression. The threeheads of the trapezius muscle work in conjunction withall other muscles that attach to the scapula to allow itto serve as a stable but moving platform.

In addition to these actions, upward rotation of thescapula occurs as a result of the combined activity ofthe upper and lower trapezius and the serratus ante-rior. Because the lower portion of the trapezius isattached to the spine of the scapula and the uppertrapezius is attached to the lateral third of the clavicleand acromion, the combined action of those two por-tions of the trapezius contributes a force coupled to thescapula that results in an upward rotary movement ofthe scapula on the thorax. Note also that any move-ment of the scapula results in motion at the

acromioclavicular and sternoclavicular joints (Figure 3-11). Also the scapula is pivoted over the rib cage, withthe lower trapezius fixing the medial aspect of thespine of the scapula and the upper trapezius pullingupward on the acromion and the lateral aspect of theclavicle. The middle trapezius works with the lowertrapezius to provide a strong stabilizing force by hold-ing the scapula against the rib cage, which helps to cre-ate a pivot point. In addition, the lower serratusanterior contributes to scapular rotation especially dur-ing the early phase of humeral elevation.8,49 Thisupward rotation is essential for complete elevation ofthe arm. Loss of any two of the four muscles consid-ered critical for arm elevation, the trapezius, serratusanterior, deltoid, or supraspinatus, renders it impossi-ble to actively elevate the arm.23

Often the exercises of choice for the trapezius mus-cles are shoulder shrugs against resistance. It must benoted, however, that the upper trapezius has a greaterpropensity toward type II fibers, implying moredynamic rather than postural function. We typicallyhave the patient perform a more vertical motion of thescapula initially and then gradually change the angle ofcervical and thoracic flexion during subsequent boutsof the exercise. This, combined with the introductionof slight external rotation of the humerus to encouragethe patient to retract the scapula, permits the recruit-ment of different components of the upper and middletrapezius muscles (see Table 3-3). Changing the angleand direction of movement during resistance exercisesis advantageous because it directs the training effect(strength, power, and endurance) to different compo-nents of the desired muscle groups (see Chapter 6).

For patients with altered shoulder mechanics andimpingement problems, strong shrugging exercisesmay compound their shoulder problem. Better toler-ated exercises might include those that strengthen andincrease the endurance capabilities of the lower andmiddle trapezius, such as strong scapular retractioncombined with extension and external rotation of theglenohumeral joint using free weights, mid-rowsagainst resistance, standing pulls from a power rack,and the classic “clean” component of the clean andjerk weightlifting maneuver.

THE SCAPULAR LAYER

We define the scapular layer as the levator scapulae,rhomboid major, rhomboid minor, and serratus ante-rior muscles. All of these muscles converge on the


Trapezius

Figure 3-11. The synchronous action of the uppertrapezius as it pulls up and back on the distal ¹⁄₃ of theclavicle and acromion, and the inferior and medial pullof the lower trapezius at the medial aspect of the spineof the scapula, create an upward rotation of thescapula.

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medial border of the scapula. Each of these musclesplays key roles in scapular mobility and stability, andan increased knowledge of their roles results in greaterattention toward them when designing therapeuticinterventions for shoulder disorders.22,30,38

Levator Scapulae

The levator scapulae muscle, a muscle with a sur-prisingly large cross-sectional area, attaches at thesuperior medial corner of the scapula, and from thisbroad, thick attachment it courses superior and medialto attach to the first three or four cervical transverseprocesses. The cross-sectional area of this muscle isactually greater than that of the upper trapezius,

which implies significant tension generating ability.The twisting of the muscle as it spirals up from themedial border of the scapula toward the transverseprocesses results in fibers that attach to the inferior-most aspect of the vertebral border of the scapula andinsert on the superiormost cervical transverseprocesses. Conversely, the superiormost attachment ofthe levator scapulae to the top of the superior medialborder of the scapula attaches to the lowest cervicaltransverse processes (Figure 3-12). Similar to the struc-ture of a braided rope, as the musculotendinous unittwists, it can withstand a greater tensile load as itstabilizes and elevates the scapula.

The levator scapulae muscle elevates the scapula andprovides strong stability to the cervical spine. Indeed, itscross-sectional area and spiral nature suggests that it isquite effective in carrying out these actions. In addition,it fixes the superomedial corner of the scapula, whichallows the lower portion of the serratus anterior tostrongly and upwardly rotate the scapula.32

Like many muscles of the shoulder girdle, the leva-tor scapulae is attached to moveable segments at bothends of the muscle, in this case, the scapula and thecervical spine. For motion to occur, one of the movableattachments must become stabilized. Elevation of theleft scapula via the left levator scapulae muscle, forexample, results in backward bending, left rotation,and left side bending forces being placed over the cer-vical spine as a result of levator scapulae activity. Theclinician must consider this when exercising the shoul-der girdle when injuries or degenerative changes arepresent in the cervical spine, especially if the scapu-lothoracic muscles are exercised against resistance. Theneck may need to be prepositioned in order to preparepartial unloading of injured tissues in that region.

Tenderness to palpation over the superomedialregion of the scapula is common in the examination ofpatients with neck pain or rotator cuff injuries.Because the levator scapulae is oriented to dynami-cally check anterior shear of the cervical spine, thetenderness over the superomedial aspect of thescapula may be the result of reflex muscle guardingand increased, prolonged muscle activity. This muscleguarding occurs because the cervical spine is unable totolerate the anterior shear stress that occurs as a resultof gravitational force over the cervical lordosis.

This same corner of the scapula is often a source ofpain in patients with rotator cuff injuries. The supero-medial corner of the scapula is the juncture of thescapular attachment of the levator scapulae and themedial end of the supraspinatus. Pain with palpation


Levatorscapulae

Figure 3-12. Note the attachments of the levatorscapulae as they travel superior from the vertebral borderof the scapulae and “twist” to attach to the transverseprocesses of C1 to C4. Recognize that contraction of thismuscle creates forces to both mobile attachments, whichmakes stabilizing one attachment before moving theother an important teaching point during exerciseinstruction.

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over the medial border of the scapula may be referredfrom the degenerative changes of or injury to thesupraspinatus muscle, or it may be a phenomenonassociated with the anatomical linkage between theinferior aspect of the levator scapulae muscle and themedial aspect of the supraspinatus muscle.

Obviously, the levator scapulae muscle has no directattachment to the humerus. Its action over the scapula,however, ultimately affects the mechanics and loads tothe glenohumeral joint. For example, if we sit with thetrunk slumped in a forward head, rounded shoulderposture and then attempt to elevate our arms, lesshumeral elevation is possible when compared with for-ward elevation of the arm with the scapulae in a slightlyelevated and retracted position (Figure 3-13). Given a

retracted scapula, the range of arm elevation is greaterand the compressive loading of the suprahumeralregion is minimized. When the scapula is protractedand elevated as in a forward head posture, the range isless and the force to the anterior shoulder progressivelyincreases to endrange. The important point here is thatscapular position affects the compression and shearforces generated in the articulation of the shouldercomplex. As discussed in Chapter 1, supporting struc-tures break down by either a rapid endrange movementor a gradual, progressive overload. Teaching the patientwith a shoulder compression or shear problem torefrain from allowing the scapula to migrate forwardduring activity is an important consideration in rehabil-itation programs for the injured shoulder.

The Rhomboids: Major and Minor

The next muscles we consider in the scapular layerare the rhomboid major and rhomboid minor. Thesecompanion muscles travel superior and medial fromthe vertebral border of the scapula to attach to the


Rhomboidminor

Rhomboidmajor

Figure 3-13. An example of the changes in activehumeral forward elevation with different positions of thescapula. A, Notice the less active humeral forward eleva-tion with the scapula in a protracted position. B, Anunimpeded humeral forward elevation occurs with aretracted scapula.

Figure 3-14. The rhomboid major and rhomboidminor muscles travel inferior and lateral to attach to thevertebral border of the scapulae. The muscles do not fea-ture the connective tissue matrix found in muscles likethe middle trapezius and the latissimus dorsi, which havegreater force capabilities. These muscles remain tendi-nous as they reach the vertebral border of the scapulae,where they blend into the serratus anterior. The rhom-boid minor lies just caudal to the levator scapulae. Therhomboid major is larger but remains flat and tendinousat its attachment to the spinous processes (T2 to T5).

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spinous processes of the thoracic spine (T2-5 andC7/T1 levels, respectively) (Figure 3-14). The rhom-boid minor attaches to the vertebral border of thescapulae just caudal to the levator scapulae, whereasthe rhomboid major covers the entire vertebral borderof the scapula.

The rhomboid muscles are quite tendinous and flatat their attachments to the spinous processes and thenbecome thicker as they course toward the scapula. Atthe medial border of the scapula they blend with theserratus anterior. The serratus anterior then coursesanteriorly and inferiorly from this medial scapularattachment to encircle the thoracic cage and ulti-mately end over the anterolateral abdominal wall. Wedescribe the relationship of the rhomboids and theserratus anterior further in the next section.

The most inferior attachment of the rhomboidmajor is at the inferior border of the scapulae, wherethe muscle is thick and quite tendinous. The rhom-boid major is one of several muscles converging to thisbony region on the scapula. The primary concentricmuscle activity of the rhomboids is scapular retrac-tion, and because of their inferior inclination from thespinous processes, they contribute slightly to down-ward rotation and elevation of the scapula. During theacceleration phase of overhead sports in which thearm is propelled forward and accompanied by stronginternal rotation, the rhomboids contract eccentricallyto control the rate at which the scapula moves laterallyfrom the spinous processes and around the rib cage.6

The fiber orientation of the rhomboid major andlower trapezius provides another example of a cross-ing (X) relationship of muscles. This overlap of per-pendicular fibers, the inferior and laterally directedrhomboid major and the inferior and mediallydirected lower trapezius, occurs in the space betweenthe vertebral border of the scapula and the spinousprocesses (Figure 3-15, A and B). Rowing exercises areconsidered one of the most effective types of exercisesfor strengthening the rhomboids.29 As mentioned pre-viously, give primary consideration in strengtheningprograms to muscles oriented in this manner. Table 3-4 lists several exercises that focus on this importantscapular layer of muscles.

Serratus Anterior

We describe the serratus anterior muscle last in thisscapular layer. From its attachment to the entirevertebral border of the ventral surface of the scapula,the serratus anterior travels anteriorly and inferiorly to


Trapezius(lower)

Rhomboidmajor

X

Figure 3-15. A and B, The crossing relationship of thelower trapezius and the rhomboid major suggests theimportance of stability and strength and represents afocus for strengthening exercises. In view A, the inferiorborder of the left scapula is marked by the X.

A

B

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attach to the first 10 ribs via a series of muscular inter-digitations. The lower four interdigitations convergefanlike to blend with the muscular interdigitations ofthe external abdominal oblique.52

The attachment of the serratus anterior at the ver-tebral border of the scapula is also continuous withthe rhomboid major and minor muscles. At the verte-bral border of the scapula, the rhomboid groups, thelevator scapulae, and the serratus anterior are devoidof the typical tendinous attachment, but instead, thethick muscle bellies of the rhomboids and levatorscapulae converge to blend with the extensive muscu-lature of the serratus anterior.

At the inferior border of the scapula, the serratusanterior has a thickened accumulation of connectivetissue, suggesting that significant muscle forces aregenerated in this region (Figure 3-16, A and B). Thistendinous convergence over the inferior border of thescapulae is an amalgamation of four specific tissues:the inferiormost aspect of the rhomboid major, the


Table 3-4. Exercises for the Scapular Layer

Levator Scapulae

Shrugs: standing straight and slightly forward bentLow rows: one foot forward, emphasis on scapular elevation

and retraction

Rhomboids

Pull-ups: counter weightedHigh rows with a ropeSeated rows with flexed starting positionStanding resisted trunk extensions starting with scapular pro-

traction: lift with head first and shrug and retract at end ofrange

Serratus Anterior

Push-ups (wall, floor, bench, gymnastic ball) emphasizing scapular protraction

Bench, dumbbell, cable pressesPulley protractionsSupine pulloversOverhead pressesSupine flys

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BAFigure 3-16. A and B, The inferior border of the scapula shows the thickness of tendinous tissuecaused by the convergence of four tissues: the inferiormost aspect of the rhomboid major, the serra-tus anterior, the fascia of the infraspinatus, and the teres major.

Rhomboidmajor

Infraspinatusfascia

Teresmajor

Serratusanterior

Rhomboid minor/major

Supraspinatus

Infraspinatus

Teres minor

Serratusanterior

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serratus anterior, the fascia of the infraspinatus, andthe teres major. The latissimus dorsi lies superficial tothis intersection of tissues as it courses medially fromthe humerus toward the spinous processes of the tho-racic vertebrae.

The posterior and inferior aspect of the serratus ante-rior also attaches to the undersurface of the latissimusdorsi muscle (see Figure 3-3). The latissimus dorsi thusserves as a dynamically stable base from which theserratus anterior can pull. One of the advantages ofsuch an arrangement is to extend or broaden the attach-ment of the serratus anterior. This suggests that as thisportion of the serratus anterior contracts, it pulls thelatissimus dorsi down against the rib cage and over theinferior border of the scapula, creating a compressive,

stabilizing force to the scapula. The result of such com-plex activity of the serratus anterior is that it works tostabilize the scapula, as well as contribute in guidingscapular movement during pushing or pulling activities.Exercises such as supine protraction, push-ups, wall push-ups, and cable crossover emphasizing humeral adductionand scapular protraction emphasize this function becausethey concentrate on moving the scapula irrespective ofthe humerus (see Table 3-4 and Chapter 6).

The serratus courses anteriorly around the rib cageto attach to the ribs and interdigitates with the externaloblique muscle. The fiber line of the external obliquethen becomes continuous with the internal oblique andadductor muscles of the thigh on the contralateral side.This has been referred to as the “serape effect.”27 A


A B CFigure 3-17. A, Note the continuous flow of muscles from the neck and thoracic spine via the lev-ator scapulae and rhomboid major to the serratus anterior that interdigitates with the externaloblique and illustrates the “serape effect.” The external oblique muscle fiber line can be followed tothe contralateral side toward the iliac crest. B, The lower aspect of the serratus–external obliquelinkage can be tracked below the umbilicus toward the contralateral femoral adductors. Comingfrom both sides as a wrap of muscle (the serape effect), muscular contribution to the antigravity pos-ture is ensured. C, This view emphasizes the muscle fiber line from the levator scapulae toward thecontralateral lower extremity.

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serape refers to a brightly colored woolen blanket, whichwas used as an outer garment by men in Hispanic cul-tures. The significance is not the cloak itself, but ratherthe way in which it is draped around the shoulders andacross the front of the body. This shape is similar to theorientation of these muscles, anatomically linking theneck, thoracic spine, and shoulder girdle to the pelvisand legs (Figure 3-17, A-C ).

We describe the serape of muscles as follows:

A. The levator scapulae travels inferiorly and posteri-orly to the superior medial border of the scapula,where it merges with the upper serratus anterioron the undersurface of the scapula.

B. The rhomboid major and minor anchor the scapulato the spine from the cervicothoracic junction andupper thoracic spinous process; these muscles mergewith the serratus anterior at the vertebral border ofthe scapula, and the serratus anterior then blendswith the external oblique, which results in the exter-nal oblique being:● Oriented along the same line of muscle fiber

direction as the contralateral internal oblique andiliac crest

● Aligned across the midline below the umbilicus,with the contralateral femoral adductors termi-nating into the femur

The blending of the levator scapulae and rhomboidsinto the serratus anterior can be seen in Figure 3-18,where the medial costal surface of the scapula serves asa bony transition between the muscles. The mainte-nance of the strength, power, and endurance of thesemuscles plays a significant role in the maintenance ofthe erect antigravity posture, which is important incontrolling loading and function of the base of theneck and the low back and at the suprahumeral spacein the shoulder (Figure 3-19).

Patients with impingement symptoms may demon-strate altered scapular mechanics.49 Electromyo-graphic studies suggest that decreased muscle activityin the serratus anterior and increased activity in theupper and lower trapezius above 90 degrees ofhumeral flexion may contribute to impingement syn-drome and increased glenohumeral forces.28

Underloaded conditions, and increased anterior tip-ping of the scapula above 90 degrees may also con-tribute to increased compression to the suprahumeraltissues at the subacromial space.35

Scapulohumeral rhythm (see Chapter 4) variesdepending on the arm position, the plane of move-ment, whether the motion is resisted or unresisted,and the integrity of the glenohumeral capsule.Scapular rotators provide an example of the impor-tant force couples that control motion and position ofthe scapula on the thorax. The serratus anterior gen-erates a downward pull of the scapula toward theaxilla, the upper trapezius pulls upward on thescapula toward the occiput, and the lower trapeziuspulls downward on the scapula toward the lumbarspine (Figure 3-20).

THE POSTERIOR SCAPULARLAYER

Muscles of this group attach the humerus to thescapula. They are thick and fibrous muscles built forpower, and they work together with muscles outsidethis layer to stabilize the position of the humeral head.The muscles described in this section are the infra-spinatus, teres minor, supraspinatus, deltoid, and thelong head of the triceps.


RhomboidSerratusanterior

Subscapularbursa

Figure 3-18. When the rhomboids and scapula arereflected, the costal surface of the scapula is visualizedblending the rhomboids with the serratus anterior. Notethe lack of tendinous tissue where these tissues blend intoone another, suggesting a mechanical linkage betweenthe associated groups, and also the size of the subscapu-lar bursa.

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Infraspinatus

The infraspinatus is a thick, triangular-shaped mus-cle consisting of superior, middle, and inferior headsthat fill the infraspinous fossa of the scapula. Atapproximately the middle region of the muscle, afibrous tendon centralizes and directs the pull of the

three heads of the infraspinatus muscle (Figure 3-21).The three heads join to wrap around the posterioraspect of the head of the humerus and then blend intothe superior and posterior aspect of the glenohumeraljoint capsule.

The superior head of the infraspinatus muscleattaches to the upper and medial vertebral border of the


Figure 3-19. Round shoulder and forward head posture place increased stress on three mainareas: the base of the neck, the lumbosacral junction, and the suprahumeral space. All areaffected by a loss of strength of the musculature that stabilizes the antigravity posture. (FromPorterfield JA, DeRosa C: Mechanical neck pain: perspectives in functional anatomy, Philadelphia, 1994,WB Saunders.)

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infraspinous fossa and to the inferior surface of the spineof the scapula. These fibers travel laterally to contributeto the formation of a broad, flat tendon that attaches tothe posterior and superior aspect of the greater tubercleof the humerus. The middle head is more fan shapedand terminates primarily into the central thickened ten-don. The inferior head of the infraspinatus muscle isattached to the inferior border of the scapula, and itsfibers are directed toward the central thickening. It tooconverges into the flat tendon that wraps around theposterior and superior aspect of the head of thehumerus. This characteristic attachment of the muscleto the humeral head allows it to contribute to gleno-humeral stability in a unique manner. Because of themanner in which the infraspinatus tendon wrapsaround the head of the humerus, it serves as a passiveconnective tissue restraint to posterior subluxation anda dynamic restraint to anterior subluxation of thehumeral head on the glenoid.

The dynamic restraint to anterior translation of thehumeral head is especially important to consider. Inthe presence of anterior glenohumeral joint instability,

attention is often paid to the strength and mass of theanterior glenohumeral muscles. It is the infraspinatusmuscle, however, with its unique attachment methodof wrapping around the head of the humerus, cou-pled with its interplay with its investing fascia,thatplays a greater role in the dynamic restraint to anteriorsubluxation.4

The infraspinatus muscle has a greater cross-sectional area than is commonly appreciated(Figure 3-22, A and B). This suggests the muscle’simportance in generating the forces required to centerthe humeral head and assist in checking the forwardand superior migration of the head of the humerus. Itis also covered by the dense infraspinatus fascia, whichserves as an anchor for the muscle to attach to, aug-menting the mechanics of this important muscle (seeFigure 3-22). Fascial coverings are typically strategi-cally placed in areas where control and stability areessential. The thoracolumbar fascia, the fascia lata inour thighs, and the abdominal fascia are examples ofkey fascial units in the body that encase muscles andprovide them a place to attach. Thus contraction of


Elevation Depression Adduction(retraction)

Lateral rotation

Medialrotation

Abduction(protraction)

Figure 3-20. Note the highdegree of scapular mobility on thethorax and the musculature thatmust work in concert synergisti-cally to permit smooth and timelymotion. Also, recognize that theloads and forces generated to theglenohumeral joint vary depend-ing on the position of the scapula.

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muscles attached to the fascia increase fascial tensionand muscles contracting within the fascial envelopealso increase tension via the broadening effect of themuscle’s contraction. These musculofascial relation-ships protect areas of the skeleton that are particularlyvulnerable to overuse.

Muscles contained within a fascial covering use thetight fascial covering to improve the mechanicaladvantage of the contraction. As the muscle contractswithin the fascial covering, it pushes against the innerwalls, which immediately directs tensile forces throughthe tendon to the bone. A system with these mechan-ics loses its efficiency as the muscle atrophies. The lossof mass of the infraspinatus muscle, either by aging orinjury, decreases the efficiency at which the muscleworks to appropriately direct the force of muscle con-traction to the skeleton. When this atrophy is coupledwith muscular fatigue, the muscular contribution toposture and movement is even further compromised.In the case of the infraspinatus muscle, the ability tostrongly center the head of the humerus on the

glenoid may be compromised and result in compres-sion of the suprahumeral tissues between the head ofthe humerus and coracoacromial arch.

At the glenohumeral joint the infraspinatus musclefunctions with the other rotator cuff muscles to centerthe head of the humerus into the glenoid.36 Thesupraspinatus muscle is very important because it isthe only muscle that is more active than the infra-spinatus muscle in shoulder motions.32 Acting alone,the infraspinatus becomes an external rotator andhumeral head depressor creating a posterior and infe-rior shear of the humerus on the glenoid. The infra-spinatus is also one of the primary decelerators of thethrowing arm. This deceleration function is often oneof the reasons for breakdown on the undersurface(articular surface) of the infraspinatus tendon. Thetensile stress imparted to the tendon during decelera-tion, coupled with the frictional force of the tendonover the rim of the glenoid, renders the tendon vul-nerable to disruption of its fibers.37 In addition, thereis an extreme distraction force between the humerusand the glenoid near the instant of ball release inthrowing and throughout the deceleration phase. Thisdistraction is resisted by the strong eccentric contrac-tion of the infraspinatus and renders this musclesusceptible to tensile overload.51

Like most muscles associated with the shouldercomplex, as the position of the humerus changes, thefunction of the muscle changes. For example, asthe humerus is elevated to 120 degrees in the scaptionplane, the infraspinatus muscle is now best aligned toexert an active compressive force between the head ofthe humerus and the glenoid fossa along with thecombined motion of horizontal abduction and exter-nal rotation. This is an optimal position to considerusing when designing resistance exercises for the infra-spinatus muscle. When the arm is at the side, the infra-spinatus muscle fibers are more aligned to produceposterior translation, inferior translation, and lateralrotation of the humerus on the glenoid. Even thoughthis is often the position to begin external rotationexercises in postsurgical conditions of the shoulder, itis not the position that optimally aligns the fibers ofthe infraspinatus muscle.

Teres Minor

The teres minor muscle is slightly fusiform in shapeand attaches to the lateral border of the scapula justbelow the inferior head of the infraspinatus. Because


Infraspinatus(superior head)

Infraspinatus(inferior head)

Infraspinatus(middle head)

Figure 3-21. The infraspinatus muscle has three heads:superior, middle, and inferior. Note the central tendonthat serves as an attachment of the angled fibers of thesuperior and inferior heads and as a tendon of the fanshaped middle head. These three heads terminate into aflat tendon that covers the posterior aspect of the head ofthe humerus.

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of its location, the narrow medial attachment is alsoattached to the infraspinatus fascia. From these pointsit courses laterally and flattens as it attaches to thehead and neck of the humerus (Figure 3-23, A and B).It spreads to cover the inferior extent of the posteriorglenohumeral joint capsule. Although supplied with adifferent peripheral nerve (the axillary nerve) than theinfraspinatus muscle (suprascapular nerve), its unop-posed actions are similar: to depress and externallyrotate the humerus. The muscle also functions with itsanterior counterparts to center the head of thehumerus in the glenoid. Acting eccentrically, the teresminor serves to decelerate the humerus during throw-ing activities and stabilizes the head of the humerusagainst anterior subluxation.

Supraspinatus

The supraspinatus muscle arises from the supra-spinous fossa and supraspinatus fascia. Although themedial attachment is thin, owing to the decreaseddepth of the medial aspect of the supraspinousfossa, the muscle becomes thicker as it travels later-ally below the acromion.16 In this region the muscle

gives rise to a flat tendon that attaches to the supe-rior facet of the greater tubercle of the humerus andblends with the capsule of the glenohumeral joint.The coracoacromial ligament lies anterior to thesupraspinatus tendon, and the infraspinatus muscletendon lies posterior.

Three different muscular heads, structured like abraided rope, can be seen on close inspection (Figure3-24). The anterior head travels posteriorly, the middlehead directly laterally, and the posterior head, whicharises from the spine of the scapula, courses anteriorly,forming a type of helical weave. The tendon of theposterior head, thinner in cross section compared withthe middle and anterior sections, overlaps the tendonof the anterior head. The intertwining of the anterior,middle, and posterior heads of the muscle results in anenhanced ability to dilute tensile stresses. The tensilecapabilities are such that the posterior fibers are theweakest whereas the anterior are the strongest andmost elastic.16 The primary roles of this muscle are toinitiate and contribute to glenohumeral abduction andto increase compression between the head of thehumerus and the glenoid. It is the most active of anyof the rotator cuff muscles and is involved with anymotion that elevates the arm.15


Humerus

Humerus

Infraspinatus

Infraspinatus

ScapulaTendon

Scapula

Tendon

MUSCLE AT REST

CONCENTRIC CONTRACTION

Fascia

Infraspinatus

Figure 3-22. A, A cross section of the infraspinatus shows how it is contained within the infraspina-tus fascia. Note how the fascia blends into the conjoint tendon and the posterior musculature. B, As thismuscle concentrically contracts, it broadens and becomes thicker, which creates tension to the fascia.This tension increases and augments a posterior and inferior pull of the muscle to its tendon.

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The supraspinatus, infraspinatus, and teres minormuscles together form an expansive, domelike tendonthat blends directly into the joint capsule covering thesuperior and posterior aspect of the head of thehumerus.2,43,45 The actions of these three muscles, inconcert with the subscapularis muscle, center andstabilize the head of the humerus in the glenoid bycounterbalancing the superior directed force the del-toid has on the humerus during elevation and checktranslations of the head of the humerus that mightoccur when other muscles attached to the humeruscontract. For example, contraction of the latissimusdorsi would pull the head of the humerus inferiorlyand posteriorly, whereas contraction of the ster-nocostal portion of the pectoralis major would pull thehead of the humerus inferiorly and anteriorly. In orderfor these muscles to carry out their actions, thehumeral head must be fixated in the glenoid socket viathese rotator cuff muscles. The infraspinatus and teresminor also function to pull the head of the humerusinferiorly, away from the acromion and coracoacro-mial ligament (suprahumeral hood) (Figure 3-25).

Within the glenohumeral joint capsule, the longhead of the biceps brachii is positioned between thesupraspinatus and subscapularis tendons. This routeacross the top of the head of the humerus allows it tocontribute to stabilization of the humeral head withthe rotator cuff (Figure 3-26). Because of its location,however, the biceps tendon, like the adjacentsupraspinatus tendon, is often involved in impinge-ment syndromes in the shoulder.40

The intricate arrangement of converging tendonsand capsular tissue of the glenohumeral joint con-tributes to control of the relationship between thehead of the humerus and glenoid throughout allranges of motion (Figure 3-27). The microscopicanatomy of this conjoint tendon is just as complex.Clark and colleagues have described five microscopiclayers of this conjoint tendon, which essentially fillsthe suprahumeral space (Figure 3-28).5 The mostsuperficial layer is primarily ligamentous tissue of theacromioclavicular ligament. The second layer consistsof closely packed tendinous tissue that connects themuscle belly to the bone. Layer three of the rotatorcuff tendon is also composed of tendinous tissue madeup of smaller fascicles. The fiber orientation of thislayer is less compactly arranged. Layer four is com-posed of collagen fibers in loose connective tissues thatrun perpendicular to one another. This layer incorpo-rates the deep portion of the coracohumeral ligament.The fifth and deepest layer of the rotator cuff tendon


Infraspinatus

Acromionprocess

Teresminor

Conjointtendon

Infraspinatus

Teresminor

A

B

Figure 3-23. A and B, A posterior view of the attach-ments of the infraspinatus and teres minor to the head ofthe humerus shows the absence of a distinct separationbetween the tendons. Instead the tendons blend togetherto unite with the joint capsule and to cover the posterioraspect of the humerus.

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is randomly organized capsular tissue surrounding theglenohumeral joint.

The superficial (bursal) surface of the tendons is thusdifferent from the deep (articular) surface.9,10,31,48

Aging of the tendons is progressive, is characterized bydecreased cellularity and vascularity, and typically isseen on the undersurface of the cuff tendons first.44 Asthe tendon ages, the articular portion of the tendonbecomes more rigid and granular and less vascular.Tears to the tendon can either be on the articular sideor spread through the midsubstance to the bursal side.Tears are also seen on the bursal surface alone (Figure3-29, A-C ). The articular side of the supraspinatus ten-don is more susceptible to mechanical failure than thebursal or midsubstance portions, with partial thicknesstears on the joint side being very common. Tears of therotator cuff tendon are often classified as small (lessthan 1 cm), containing only the supraspinatus tendon,

to massive (greater than 5 cm), which include thesupraspinatus, infraspinatus, and subscapularis tendons(Figure 3-30, A-D).14

Partial and full thickness tears are commonly seen asa result of athletic and work activities that involverepetitive overhead motions and contact sports.3,46

Rotator cuff injuries lead to glenohumeral instabilityand are contributing factors to impingement syn-dromes. Prolonged and progressively increased pres-sure weakens the connective tissues of the coraco-acromial arch, stiffens the coracoacromial ligament,causes traction spurs to form on the acromion andcoracoid processes, and weakens the cuff tendons,resulting in decreased tissue tolerance.48 The soft tis-sues of the coracoacromial arch (see Chapter 4) pro-vide some force attenuation abilities; however, thechanges seen at the undersurface of the acromion andthe thickening of the coracoacromial ligament suggest


Infraspinatus

Spine ofscapula

Supraspinatus

Clavicle

Cuff tendons

Figure 3-24. A superior view of the supraspinatus muscle shows the different fiber orientations ofthe anterior, middle, and posterior portions of the muscle.

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that this area is a focus of compression in the gleno-humeral joint, thus illustrating the crucial role the cufftendons play in the centralization of the humeral headin any position.

Instability of the glenohumeral joint is also associ-ated with tears of the rotator cuff tendons. Aberrantmotions of the humerus on the glenoid occur as a resultof rotator cuff muscle and tendon failure. As in anysynovial joint, aberrant motion resulting from injury tosupporting structures of the joint predispose the articu-lation to overload and possible early degeneration.

It is important to remember that degeneration ofthe rotator cuff tendons is primarily a function of age.9Furthermore, because of the wide range of shouldermotion, continual friction between the undersurfaceof the tendon and the glenoid rim, and the

hypovascularity of the rotator cuff tendons, lesions ofthe cuff tendons do not heal spontaneously.54 Thishighlights the importance of maintaining muscu-loskeletal health and strength, particularly in thosemuscles focused over the thoracic spine, trunk, andscapula that maintain our erect posture. Table 3-5 listsseveral key exercises used in maximizing shoulder func-tion, including those with a strengthening effect to therotator cuff. Historically, exercise for the supraspinatuswas prescribed with the arm in the thumb down(“empty can”) position. Placing the glenohumeral jointin this position and then performing resistance exer-cises significantly compromises the tendon and placesthe supraspinatus at further risk.17 We encourage alloverhead resistance exercises to be performed with thehumerus in the laterally rotated position.

Deltoid

The thick, triangular-shaped deltoid muscle hasthree heads: anterior, middle, and posterior (Figure3-31). The anterior, attaching to the lateral third ofthe clavicle, and the posterior, which attaches to thespine of the scapula, are essentially parallel to each


Supraspinatus

Infraspinatus

Subscapularis

Bicepstendon

Figure 3-25. The downward pull of the infraspinatusand teres minor muscles can be seen as the humerus isabducted. Without this balance of forces, the chances ofexcessive compression forces between the head of thehumerus and the acromion and coracoacromial ligamentare high. (Modified from Kapandji IA: The physiology ofthe joints: annotated diagrams of the mechanics of the humanjoints, New York, 1982, Churchill Livingstone.)

Figure 3-26. Note the route of the long head of thebiceps tendon as it passes over the head of the humerusand blends with the conjoint tendon of the supraspinatusand infraspinatus muscles.

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other and cover the front and back of the shoulder.The middle deltoid is actually composed of four sep-arated multipennate, coarsely structured sectionstraveling inferior from the acromion. It joins with theanterior and posterior heads to attach via a short

tendon to the deltoid tuberosity on the lateral distalhumerus. The three heads of the deltoid check theinferior migration of the humeral head on the gle-noid. Other muscles assisting the deltoid in this func-tion include the long head of the triceps,coracobrachialis, and short head of the bicepsbrachii. The anterior deltoid is a strong sagittal planeelevator and internal rotator of the humerus, themiddle deltoid a frontal plane elevator (abductor) ofthe humerus. The posterior deltoid extends, hyperex-tends (being the only muscle with this capability), andexternally rotates the humerus.

Figure 3-32 illustrates a horizontal section thatdemonstrates the differences in structure between theanterior and posterior deltoid. Note the difference inmass between the anterior muscles, such as the ante-rior deltoid and pectoralis major, and the posteriordeltoid and scapular muscles. The posterior musclesare quite substantial by comparison, which suggeststhe importance of emphasizing the posterior muscula-ture in exercise programs. Exercises emphasizingpulling up and back, and down and back withoutexacerbating shoulder pain, and learning (teaching) toappropriately direct the force of the exercise towardthe intended musculature are essential in designingexercises for the shoulder.

The deltoid tuberosity, serving as the point ofhumeral attachment, lies approximately halfway downthe lateral shaft of the humerus. When the line ofmuscle pull is analyzed from the acromial end to thehumeral end, we can see that the action of the muscleover the lever of the humerus is dependent on the


Coracohumeralligament

Supraspinatus

Infraspinatus

Capsule

Subscapularis Capsule

Teres minor

InfraspinatusSupraspinatus

Biceps tendon (long head)

Figure 3-27. The deep struc-tural arrangement of the conjointtendon of the rotator cuff locatedat the head of the humerus con-sists of the biceps tendon andfour muscles: the subscapularis,the supraspinatus, the infraspina-tus, and the teres minor.(Modified from Clark JM,Harryman DT II: Tendons, liga-ments and capsule of the rotatorcuff, (J Bone Joint Surg Am74(5):717, 1992.)

Figure 3-28. Note the layered anatomy of thesuprahumeral tissues. (Modified from Clark JM,Harryman DT II: Tendons, ligaments and capsule of therotator cuff, J Bone Joint Surg Am 74(5):723, 1992.)

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glenohumeral joint angle. From the resting, anatomi-cal position, the line of deltoid muscle pull on thehumerus is primarily superior translation of thehumerus. Conversely, it is markedly active between 90and 180 degrees of elevation.47 As the arm is raisedfurther in the frontal plane, there is less force of

superior translation and an increasing force of gleno-humeral compression.

Once the humerus reaches approximately 20degrees of abduction, the deltoid line of muscle pullbegins to be positioned to allow it to serve as a pow-erful elevator of the humerus in the frontal, sagittal,and scaption planes, but only if the rotator cuff hascentralized and fixated the humerus within the shal-low glenoid. Note also that the line of pull of thelatissimus dorsi and sternocostal portion of the pec-toralis major counterbalances the deltoid pull as well(Figure 3-33). Without these counterbalances, themiddle deltoid muscle simply drives the head of thehumerus superiorly into the acromion, coracoacro-mial ligament, coracoid process, or tendons of thepectoralis minor, coracobrachialis, and short head ofthe biceps brachii. Figure 3-34 illustrates the differ-ences in forces at the suprahumeral space below60 degrees and above 120 degrees with a retractedscapula.

Long Head of the Triceps

The long head of the triceps is the final muscle wediscuss in the posterior scapular layer. From its distalattachment at the olecranon of the ulna, the longhead travels superiorly and medially to pass betweenthe teres major and teres minor muscles, attaching tothe infraglenoid tubercle of the scapula. This inter-section with the teres major and minor creates thequadrangular and triangular spaces (Figure 3-35).The axillary nerve and the posterior humeral circum-flex vessels travel through the quadrangular space asthey course around the neck of the humerus, whereasthe triangular space houses the scapular circumflexvessels.

The crossing of the teres group and the tricepsmuscle provides yet another example of the crossingrelationship of muscles potentially adding stability tothe area, in this case the posterior and inferior aspectto the glenohumeral joint. A similar crossing relation-ship lies anterior to the glenohumeral joint, consistingof the crossing relationship between the subscapu-laris, coracobrachialis, and short head of the biceps.Together the weave of muscles formed by these pos-terior and anterior crossing relationships addsincreased stability to the inherently unstable gleno-humeral joint (Figure 3-36).

The long head of the triceps helps minimize infe-rior translation of the humeral head on the glenoid


A

B

CFigure 3-29. Three locations of rotator cuff tears: A, Bursal side; B, articular side; and C, midsubstance.The articular side tears are most commonly seen.(Redrawn from Hawkins RJ, Bell RH, Lippitt SB: Atlas ofshoulder surgery, St. Louis, 1996, Mosby.)

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when an inferior shear force is introduced. Con-traction of the long head pulls the humerus superi-orly, resulting in superior translation of the humeralhead at the glenohumeral joint. The patient with ahemiparetic arm or one who has had a radial nerveinjury may exhibit inferior subluxation of the

humerus because of the loss of this triceps muscle sta-bilizing function over the glenohumeral joint. Otherfunctions of the long head of the triceps includepulling the humerus back down to the anatomicalposition from starting points of glenohumeral eleva-tion, such as in “chopping” strokes that extend oradduct the arm. At the elbow, the triceps contributesto elbow extension with its associated lateral andmedial heads.

We can see through this discussion that groups ofmuscles work together to form a system of counterbal-ances and muscular reinforcements via crossing rela-tionships that work to check the inferior-superior andthe anterior-posterior migration of the head of thehumerus. Concentric contraction of the long head ofthe triceps, the short head of the biceps brachii, cora-cobrachialis, clavicular head of the pectoralis major,and deltoid have a line of muscle force that pulls thehumerus superiorly, whereas the eccentric activity ofthese same muscles controls inferior movement of the


Infraspinatus

Supraspinatus

Infraspinatus Infraspinatus

Infraspinatus

Supraspinatus

Supraspinatus

Supraspinatus

Subscapularis

Subscapularis

Subscapularis

SubscapularisCoracoacromialligament

Clavicle

Figure 3-30. Note the size of rotator cuff tears. These tears are classified as A, small, to D, massive. Note how the head of the humerus rides up through the tear. (Redrawn fromHawkins RJ, Bell RH, Lippitt SB: Atlas of shoulder surgery, St. Louis, 1996, Mosby.)

Table 3-5. Exercises for the PosteriorScapular Layer

Superior Cuff, Posterior Cuff, Posterior Deltoid

Low row with external rotationPNF cable resistance patterns: horizontal abduction and

external rotationSeated rowReverse flyForward elevations and overhead pressesLateral shoulder raises

A B

C D


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humerus (Figure 3-37, A). We refer to these muscles as“hanger muscles” because they dynamically suspendthe humerus at the glenoid. These muscles are coun-terbalanced by the line of pull offered by the latissimusdorsi, teres major, teres minor, the inferior head of theinfraspinatus, inferior head of the subscapularis, and

the costal portion of the pectoralis major, which exertan inferiorly directed line of force over the humeralhead (Figure 3-37, B). Coordinated muscle activityhelps ensure that the forces of gravity and the contrac-tile forces of movement secure the position of thehumeral head in the glenoid.


ANTERIOR

Deltoid

Teresminor

ScapulaInfraspinatus

SubscapularisPectoralis

major

Deltoid

Teresminor

ScapulaInfraspinatus

SubscapularisPectoralis

major

Serratusanterior

ANTERIOR POSTERIOR

Figure 3-31. Three heads of the del-toid muscle are shown in these anteriorand posterior views. Note these differ-ent directions of the muscle’s fibers;each muscle fiber orientation is focusedtoward one central point on the deltoidtuberosity.

Figure 3-32. A horizontal cross section of the shoulders at the region of the mid-humerus showsthe relationships and relative thickness of the muscles of the anterior and posterior shoulder.

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THE SUBSCAPULAR REGION

The subscapular region includes the serratus ante-rior and subscapularis muscles and can be approachedduring dissection in several ways. One of the bestapproaches, which allows us to better appreciate themovement potential of the scapula on the thorax, is aposterior approach. By reflecting the trapezius andrhomboid muscles from the spine of the scapula, weessentially free the scapula from the spinous processes.From this vantage point, the costal surface of thescapula can then be explored.

Serratus Anterior

One of the first structures encountered during dis-section of the subscapular region from a posteriordirection is the subscapular bursa. This large andexpansive tissue comes into view when the rhomboidshave been reflected from the spinous processes, allowingthe costal surface of the scapula to be explored. Theserratus anterior muscle is easily seen where it attachesto the vertebral border of the scapula. The largesubscapular bursa lies between the serratus anterior andthe underlying small muscles of respiration consisting ofthe serratus posterior superior and intercostal muscles.The bursa is quite extensive, typically exceeding thedimensions of the scapula, and it serves to form a rela-tively friction free environment for these tissues to moverelative to one another (see Figure 3-18).


<60�

>60�

>120�

Tmi

TM

LD

D

PM

Figure 3-33. This schematic illustration shows thedownward pull of the latissimus dorsi (LD), teres major(TM), teres minor (Tmi), and the costal portion of thepectoralis major (PM) to counterbalance the superiormigration of the humerus as a result of the contractionof the middle deltoid (D) muscle. (Modified fromKapandji IA: The physiology of the joints: annotated diagramsof the mechanics of the human joints, New York, 1982,Churchill Livingstone.)

Figure 3-34. Three frontal planeviews of the glenohumeral articu-lation show the shear and com-pression of the suprahumeraltissues below 60 degrees, between60 and 120 degrees, and above120 degrees. Note the importanceof scapular position in the analysisof these forces.

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The extremely important role that the serratusanterior plays in concert with the rhomboids, levatorscapulae, and external oblique has already beendescribed in previous sections of this chapter. The dis-cussion now focuses on how the shoulder girdle is tiedthrough a system of muscles to the trunk and lowerextremities through the serape effect. Acting alone, theserratus anterior line of muscle pull allows for pro-traction and upward rotation of the scapula.

The upward rotation function of the serratus ante-rior is extremely important, since it is one of the fewmuscles capable of this important action, the otherbeing the combined effort of the upper and lowertrapezius. Often individuals engaging in upperextremity exercise programs fail to complete the strokeof humeral elevation exercise, meaning that the strongupward rotation of the scapula as they work to elevatetheir arms against resistance is lacking. Failure to do soleaves the elevated shoulder (arms overhead) in a posi-tion of downward scapular rotation, thereby increas-ing subacromial compression. Therefore it is essentialthat the scapula be monitored for full and strongupward rotation activity during any shoulder elevationexercise. The anatomy of the serratus anterior sug-gests how important this upward rotation function is;the heaviest serratus anterior attachment is at theimportant inferior angle of the scapula.

Likewise, pushing exercises such as bench presses,dumbbell presses, and supine horizontal “fly” exercises(see Chapter 6) must emphasize scapular protraction in


Triceps(longhead)

Coracobrachialis

Bicepstendon

(short head)

Bicepstendon

(long head)

Bicepsbrachii

Subscapularis Teres minor

Teresmajor

ANTERIOR POSTERIOR

Circumflexscapular

artery

Teresmajor Triceps

Posteriorcircumflexhumeralartery

Axillarynerve

Teresminor

Figure 3-35. A posterior view of the right shouldershows the relationship of the long head of the triceps,teres major, and teres minor muscles. Note the crossingrelationship of the teres major and the long head of thetriceps, which forms a quadrilateral space laterally andthe triangular space medially. These spaces house theaxillary nerve and the posterior humeral and scapularcircumflex arteries.

Figure 3-36. The crossing rela-tionship posterior to the gleno-humeral joint from the long headof the triceps and the teres musclesforms an X close to the posteriorand inferior aspect of the gleno-humeral joint. A complement tothis X is seen on the anterior sidewhen the coracobrachialis, shorthead of the biceps brachii, and thesubscapularis are viewed.

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order to be effective. If exercising focuses only onmovement of the humerus, we do not benefit from itsmost important aspects: moving the scapula from aposition of retraction to an endrange of protraction.This activity is a function of concentric action of theserratus anterior, whereas the eccentric activity of themuscle allows for a controlled return to a retractedscapular position.

Subscapularis

If the serratus anterior is detached from the ver-tebral border of the scapula and the scapula liftedaway from the thorax, the subscapularis muscle

comes into view where it is positioned between theserratus anterior muscle and the subscapular fossa.The subscapularis has three heads as it lies on thesubscapular fossa (Figure 3-38). This muscle is quitethick and like the infraspinatus has muscular fibersconverging from a wide medial position toward acentral tendon covering the anterior aspect of theglenohumeral joint. The superior head originatesfrom the superior portion of the subscapular fossaand travels slightly inferiorly and laterally, whereasthe fan-shaped and thinner middle head travels lat-erally. The inferior head is thicker and exhibits astronger looking stature, and the majority of thesubscapular tendon appears to be associated withthe inferior head.


SS

PM

I

Tmi

TM

LD

SP D

D

C

T

D

PMBL

BS

Figure 3-37. A, “Hanger muscles” check the inferior migration of the humerus and include thetriceps (T), short (BS) and long (BL) head of the biceps brachii, coracobrachialis (C), clavicular headof the pectoralis major (PM), supraspinatus (SP), and deltoid (D). Their eccentric contraction con-trols the inferior migration of the humeral head. B, Muscles that, during concentric contraction, pullthe humerus down place a counter force to the hanger muscles ensuring proper positioning of thehead of the humerus. These muscles include the latissimus dorsi (LD), teres major (TM), teres minor(Tmi), the inferior head of the infraspinatus (I) and subscapularis (SS), and the costal portion of thepectoralis major (PM). (Modified from Kapandji IA: The physiology of the joints: annotated diagrams of themechanics of the human joints, New York, 1982, Churchill Livingstone.)

A

B

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The tendon of the subscapularis has the largest crosssection of any tendon in the shoulder (Figure 3-39).This broad tendon covers the anterior shoulder anddynamically reinforces the anterior aspect of theshoulder, including the anterior aspect of the glenoidlabrum and the glenohumeral ligaments. Actingunopposed, the subscapularis internally rotates thehumerus, and with the arm in the anatomical position,the angled fibers of the inferior head create an inferi-orly directed force to the proximal humerus. As thehumerus changes position, however, the muscle adoptsdifferent functions. For example, as the humerus isabducted and externally rotated, the angle of thefibers of the muscle changes so that contraction ofthe subscapularis serves to compress the head of thehumerus into the glenoid and provide some contribu-tion to glenohumeral adduction. Perhaps most impor-tantly, the subscapularis is the major dynamic restraintto posterior instability of the glenohumeral joint.39

As described above, there are always counterbal-ancing muscular forces that ensure the proper balancebetween joint mobility and stability. The inferiorlydirected fibers of the large, anteriorly placed inferiorhead of the subscapularis are counterbalanced by theposteriorly placed fibers of the inferior head of theinfraspinatus and the teres minor muscles, providing adynamic restraint to anterior posterior translation. Inboth muscle groups the anterior subscapularis and


X

Subscapularis (superior head)

Subscapularis(middle head)

Subscapularis(inferior head)

Figure 3-38. The superior, middle, and inferiorheads of the subscapularis muscle show that the infe-rior head is larger and contributes to the majority ofthe tendon.

Figure 3-39. The cross section of thesubscapularis tendon shows the thick-ness and breadth of its structure(marked by the X). It dynamically rein-forces the anterior glenohumeral liga-ments of the joint capsule.

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posterior infraspinatus provide the counterbalance tothe superior translation of the humeral head gener-ated by the deltoid muscle (Table 3-6).

Excellent representative exercises to strengthenmuscles associated with the subscapular layer arelisted in Table 3-7. Descriptions and details are inChapter 6.

THE ANTERIOR SHOULDER

In this section we describe the sternocleidomastoid,pectoralis major, anterior deltoid, pectoralis minor,coracobrachialis, and both heads of the bicepsbrachii. We begin medially at the sternoclavicularjoint and move forward laterally toward the gleno-humeral joint.

Sternocleidomastoid

The sternocleidomastoid muscle is a superficialmuscle arising from the mastoid process. It lies in thesame plane as the trapezius muscle and is similarlycovered with the investing fascia of the neck. Likethe trapezius muscle, it is innervated via the spinalaccessory nerve. From the occiput, the muscle anglestoward the midline and divides into two heads onreaching the anterior aspect. The smaller sternalhead attaches to the manubrium of the sternum,and the broader clavicular head attaches to themedial aspect of the clavicle (Figure 3-40). Theanterior costoclavicular ligament is oriented as acontinuation of the line of pull of this muscle andserves to transfer the superiorly directed force of theclavicular head of the sternocleidomastoid muscle tothe first rib via this ligamentous attachment from theclavicle to the rib.

Because the sternocleidomastoid muscle lies super-ficially, it is easily seen during the physical examinationof the patient. When the head and neck are properly


Table 3-6. Counterbalancing Muscles of the Glenohumeral Joint

Muscles Pulling Humeral Head Superiorly

Triceps (long head)Biceps brachii (short head)CoracobrachialisClavicular head of the pectoralis majorDeltoid

Muscles Pulling Humeral Head Inferiorly

Latissimus dorsiTeres majorTeres minorInfraspinatus (inferior head)SubscapularisPectoralis major (sternocostal head)

Table 3-7. Exercises for Muscles of theSubscapular Layer

Supine flys: emphasize arc of motionPullovers from supinePush presses emphasizing scapular protractionBench presses emphasizing scapular protractionUpward rotation of scapula with humerus held at 90 degrees

elevation and full external rotationPush-ups with protraction at endGymnastic ball push-ups with protraction at endOverhead pressesPNF pulls across the body with internal rotation and

scapular protraction emphasis

Sternocleidomastoid

Sternal head

Clavicular head

Figure 3-40. The sternocleidomastoid muscle arisesfrom the mastoid process and travels inferiorly and ante-riorly to form two heads. The clavicular head attaches tothe medial clavicle, and the sternal head attaches to thesternum.


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aligned over the thoracic spine and shoulder girdle,the muscle can be seen in its normal oblique orienta-tion. If the sternocleidomastoid is oriented more ver-tically instead of obliquely, it cues us that a forwardhead posture is present.

The several actions of the sternocleidomastoidmuscle include its extension of the occiput on theatlas, flexion of the lower cervical spine, rotation ofthe cervical spine contralaterally, lateral flexion of thecervical spine, and the ability to bring the head andneck forward. This forward head posture is one thatplaces the sternocleidomastoid muscle in a short-ened position and is a posture often assumed follow-ing hyperextension injuries of the neck since theposture places the injured musculature in a restposition.

Although not considered part of the anteriorshoulder musculature, the position of the subclaviusbears mentioning at this point. The small subclaviusmuscle attaches to the inferior surface of the clavicleand travels inferiorly and anteriorly to attach to thesuperior surface of the first rib. It assists in providinga check and balance of the forces and loads that aredirected into the sternoclavicular joint and ulti-mately pass through the shoulder complex (Figure 3-41). The inferior pull of the subclavius on theclavicle, in combination with the costoclavicular lig-aments, counterbalances the pull of the sternoclei-domastoid muscles.

Pectoralis Major

The upper part of the pectoralis major muscleoriginates from the sternal half of the clavicle andtravels directly laterally to attach to the lateral lip ofthe bicipital groove. The middle or sternocostalaspect of the pectoralis major takes attachment fromthe manubrium, sternum, and the upper ribs. Itcourses laterally, and its tendon attaches just poste-rior to the tendon of the clavicular head. Theabdominal head of the muscle takes origin from thelower ribs and the abdominal fascia and courses tothe lateral lip of the bicipital groove but does so bytwisting on itself. As a result, the lower fibers of thisportion of the muscle insert highest on the humeruswhereas the upper portion of the abdominal headfibers insert lowest on the humerus. This results inthe tendinous insertion of the muscle taking the formof a highly complex amalgamation of connective tis-sue oriented in a trilaminar complex.

As the pectoralis major tendon approaches theanterior shoulder, it also has important anatomicalrelationships with other structures. A fascial expansionfrom the tendon of the abdominal head referred to asthe falciform ligament combines with the main portion ofthe tendon to surround the tendon of the long headof the biceps brachii muscle over the intertuberculargroove of the humerus. This ligamentous expansionnot only attaches to both lips of the bicipital groove


Sternocleidomastoid

Costoclavicularligament

Sternoclavicularligament

Subclavius

Coracoclavicularligament

Figure 3-41. The inferiorcounterbalances to the superiorclavicular musculature includethe medial and lateral costoclav-icular ligament and the subclav-ius muscle.

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and helps stabilize the long head tendon but also rein-forces the glenohumeral joint capsule.

Because of the broad attachments of the pectoralismajor, the actions of the muscle are several and aredependent on the starting position of the glenohumeraljoint. From the anatomical position, the clavicular headparticipates in sagittal plane elevation. Once the arm is

overhead, the abdominal and sternocostal heads pullthe arm strongly back toward extension and adduction.The strong adduction capabilities of the pectoralismajor allow its pull also to result in depression anddownward rotation of the scapulothoracic articulation.All of the heads are aligned to contribute to internalrotation, and the combination of the latissimus dorsi,


Pectoralis (clavicular head)

Pectoralis(sternal head)

Pectoralis(abdominal

head)A

BFigure 3-42. A, The three heads of the pectoralis major muscle are: clavicular, sternal, andabdominal. The clavicular head forms the anterior lamina of the tendon and travels inferiorly andlaterally to the medial lip of the intertubercular groove. However, the sternal and abdominal headsblend and twist, forming a medial and posterior lamina that attaches to the glenohumeral joint cap-sule superiorly and surrounds the tendon of the long head of the biceps brachii muscle as it coursesthrough the intertubercular groove. The inferiormost aspect of the abdominal head attaches mostsuperior, and the superiormost aspect of the sternal head attaches most inferior. B, Note the cross-ing relationship of the pectoralis major.

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teres major, anterior deltoid, and pectoralis majormakes internal rotation a much stronger motion thanglenohumeral external rotation. Most of the pectoralismajor muscle is oriented to horizontally adduct thehumerus across the body.

In the abdominal region, the pectoralis majorblends into the abdominal fascia bilaterally to formanother crossing relationship over the anterior supe-rior aspect of the trunk. Thus contraction of the pec-toralis major muscle pulls up or “cinches” theabdominal fascia much like the latissimus dorsi overthe posterior shoulder cinches up the thoracolumbarfascia (Figure 3-42, A and B).

Anterior Deltoid

Although it was described earlier, the anterior del-toid is mentioned briefly again here because of its mus-cular attachments to the clavicle. It arises from thelateral third of the clavicle, where it helps reinforce theacromioclavicular joint, and travels posteriorly and lat-erally to merge with a central tendon that is also asso-ciated with the middle and posterior heads of thedeltoid. The tendon is thick and fibrous and inserts into

the deltoid tuberosity of the humerus. As previouslynoted, this tuberosity is located on the lateral surface ofthe humerus midway down the shaft. Unlike the mid-dle portion of the deltoid, which has several differentparts, the anterior head courses obliquely and is thusoriented to flex, internally rotate, and adduct thehumerus. The stronger the contraction of the deltoidto move the humerus, the more vigorous the activity ofthe muscles attached to the clavicle and scapula inorder to provide a stable yet moving platform.

Pectoralis Minor

With the pectoralis major and anterior deltoidreflected, we can view three muscles that are attachedto the coracoid process. These are the more mediallyplaced pectoralis minor and the laterally placed con-joint tendons of the coracobrachialis and the shorthead of the biceps brachii (Figure 3-43). The pec-toralis minor is a thin, triangular-shaped muscle thatlies directly under the pectoralis major. From the cora-coid process, it travels inferiorly and medially to attachto the second, third, fourth, and fifth ribs just lateral tothe costocartilaginous junction and the aponeurosisthat covers the intercostal muscles from ribs 2 through5. In the region of the anterior axilla, the pectoralisminor covers the neurovascular complex coursingfrom the neck to the upper extremity (see Chapter 2).

Beginning with the scapula in a starting position offull retraction, the pectoralis minor pulls the scapulaforward (protraction). Keep in mind that a position ofretraction collapses the pectoralis minor over the neu-rovascular bundle in the axilla. In the presence of neu-ral or vascular symptoms in the upper extremity, thepostural role of the pectoralis minor needs to be care-fully evaluated. If the scapula is in an upwardly rotatedposition, the pectoralis minor pulls down on the cora-coid process, resulting in downward rotation at thescapulothoracic articulation. Because of this combinedeffect of downward rotation and protraction, tightnessof the muscle may be a contributing factor in therounded shoulder posture. Finally, if the scapula is fix-ated, the muscle may act to raise the rib cage.

Coracobrachialis

The coracobrachialis muscle lies medial to but isblended with the short head of the biceps brachii atthe coracoid process. From this attachment the long


Pectoralisminor

Coraco-brachialis

Bicepsbrachii(short head)

Figure 3-43. The three muscles that attach to the cora-coid process are from lateral to medial: the pectoralisminor, the coracobrachialis, and the short head of thebiceps brachii.

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straplike muscle actually broadens quite dramaticallyas it courses inferiorly and laterally to insert on theanteromedial aspect of nearly a third of the humerusin the region between the triceps brachii and thebrachialis muscles. The coracobrachialis lies over thetop of the subscapularis muscle, and the coraco-brachialis bursa is interposed between the two. Noteagain how a crossing relationship is formed betweenthe more vertically oriented coracobrachialis and themore horizontally oriented subscapularis.

The action of the muscle is primarily elevation ofthe glenohumeral joint in the sagittal plane, as well asadduction and horizontal adduction of the humerus.When the extent of the coracobrachialis insertion onthe humerus is closely inspected, we can see how the

muscle strongly contributes to glenohumeral adduc-tion, and this is the primary motion with which themuscle is trained using resistance exercises.

Short Head of Biceps Brachii

The short head of the biceps brachii arises from thetip of the coracoid process as thick, flat tendon incommon with and lateral to the coracobrachialis mus-cle. From the coracoid process it travels inferiorly andlaterally to join the long head of the biceps, forming asingle muscle belly, which ultimately attaches to theforearm in two distinct ways. The lateral part ofthe muscle attaches to the radial tuberosity, whereasthe medial aspect of the muscle blends in with theforearm fascia as the bicipital aponeurosis (Figure 3-44).The primary actions of the biceps occur at the elbowregion and include elbow flexion and forearm supina-tion. Over the shoulder, the muscle can contribute tothe initiation of elevation of the humerus, and fromthe overhead position the muscle helps pull thehumerus down to the side of the body. The short headof the biceps and the coracobrachialis form a crossingrelationship with the subscapularis muscles, whichcontributes to the stabilization of the anterior aspectof the glenohumeral joint (see Figure 3-36).

Long Head of Biceps Brachii

The long head of the biceps brachii arises from thesupraglenoid tubercle and the posterior-superior gle-noid labrum and glenoid rim. It is enclosed in a spe-cial synovial sheath within the glenohumeral joint,and the tendon exits through an opening of the cap-sule. Such an arrangement allows the tendon to beintracapsular yet extrasynovial relative to the gleno-humeral joint. It travels over the humeral head andemerges from the capsule to lie within the intertuber-cular groove.

Several tissues stabilize the long head of the bicepsover the head of the humerus and through the bicipitalgroove. Proximally the tendon is covered by the coraco-humeral ligament and superior glenohumeral ligamentof the joint capsule, thus stabilizing the tendon in thisregion. The tendon then exits the capsule and reachesthe proximal aspect of the bicipital groove. At thisregion, the upper portion of the subscapularis tendonand lower aspect of the supraspinatus tendon form thefloor of the sheath embracing the biceps tendon.


Coracobrachialis

Biceps(short head)

Biceps(long head)

Bicipitalaponeurosis

Radialtuberosity

Figure 3-44. The short and long heads of the bicepsbrachii muscle join to form a thick, round muscle bellythat eventually twists to attach on the radial tuberosity.The bicipital aponeurosis arises from the tendon andcourses obliquely downward and medially to blend intothe fascial covering of the flexor forearm.

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Another fascial expansion from the supraspinatus com-bines with the coracohumeral ligament to cover the ten-don. Finally, as the tendon enters the main portion ofthe groove, it is covered by the falciform ligament,which is the fascial expansion of the pectoralis majortendon. The falciform ligament attaches not only toboth lips of the bicipital groove but also to the gleno-humeral capsule. Thus the long head of the biceps isstabilized at the shoulder joint via a complex array ofseveral important connective tissues.

In order to most effectively design exercise pro-grams in the presence of long head of the biceps ten-don involvement, we must realize that the long head ofthe biceps tendon does not slide in the bicipital groovebut rather the humerus moves under a stationary ten-don. The sheath that surrounds the biceps tendonhelps minimize the friction between the movinghumerus and the static tendon. Bicipital tenosynovitisis an inflammation of this tendinous sheath, and it isimportant to recognize the mechanics of the groovetendon relationship to effectively manage this condi-tion. The clinician must decrease shoulder flexion,both extension and abduction, and adduction activi-ties rather than elbow flexion and extension activitiesto successfully rest this area. Pulling exercises thatrequire the humerus to move against resistance fromflexion to extension potentially aggravate the tenosyn-ovitis problem and exacerbate the condition.

The actions of the biceps over the elbow havebeen noted previously. The long head has severalunique functions. It is a major decelerator of thethrowing arm as the elbow rapidly moves from aflexed position in the early stages of throwing to anextended position. In addition, it most likely serves asa weak flexor at the glenohumeral joint. The longhead also functions to increase stability of the gleno-humeral joint. Its very anatomical position allows itto serve as a static restraint to superior translation ofthe head of the humerus. Active contraction of thelong head only slightly depresses the humeral head,so the tendon’s role is primarily a passive one inregard to this function.53 It is important to note thatits normal static contribution is dependent on thepositioning of the tendon within the groove, which isa function of the stabilizing mechanisms provided bythe supraspinatus and subscapularis tendons. Tearsof the rotator cuff can thus affect the positioning ofthe long head of the biceps tendon, resulting in itsinability to contribute to glenohumeral stabilization.

The position of the glenohumeral joint also influ-ences the contribution of the long head of the biceps

tendon to shoulder stabilization. When the arm isplaced in a position of abduction and external rota-tion, the long and short heads of the biceps becomeanterior reinforcements to the anterior glenohumeralligaments and joint capsule. When there has beeninjury to the glenohumeral ligaments, the biceps ten-dons serve to stabilize the humeral head against ante-rior translation.18

Finally, the tendon of the long head of the bicepsbrachii passes over the head of the humerus in a posi-tion that is vulnerable to excessive compressionbetween the head of the humerus and thesuprahumeral dome. It is common for the tendon ofthe long head of the biceps brachii to flatten becauseof compression, rendering it vulnerable to swellingand possible rupture (see Chapter 4). The tendon isalso vulnerable at its attachments to the glenoidlabrum, where it can be avulsed away from its attach-ment especially as resulting sequelae to long term,continuous stress that weakens the tissue. Tears of theglenoid labrum, in particular the SLAP (superiorlabrum anterior to posterior) lesions discussed inChapter 4, can be compromised even further whentension is applied through the biceps tendon, whichplaces further stress to an already compromised gle-noid labrum. A torn labrum with a split longitudinallyin the long head of the biceps is evidence of a veryadvanced SLAP lesion.11 We can easily see that trac-tion through the long head of the biceps tendon notonly further compromises the tendon but also furtheravulses the glenoid labrum.

Exercises primarily for training the muscles of theanterior shoulder are listed in Table 3-8 and are illus-trated and discussed in Chapter 6.


Table 3-8. Exercises for the AnteriorShoulder Layer

Pectoralis: Major and Minor

Coracobrachialis

Supine flysBench pressesIncline bench pressesWeight assisted bar dipsShoulder elevations in various planes between sagittal and

frontal with external rotated humerus

Biceps Brachii

Elbow curls with simultaneous supinationSeated rows with supinationCounter weighted pull-ups with underhand grip

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ABDOMINAL MUSCULATURE

The last muscle group that should be describedbriefly in any textbook about mechanical shoulder dis-orders includes those of the abdominal wall. We havediscussed these muscles in detail in previous texts.33,34

The abdominal wall functions to maintain the cylin-der of the trunk responsible for the maintenance of anerect posture. It also serves to ensure efficient move-ment of the appendages.

The abdominal wall has four muscles directly asso-ciated with its structure, namely the transversus


Figure 3-45. A, The abdominal musculature that contains the abdominal cylinder is composed of theabdominal muscles, the diaphragm, the lumbar spine and its related muscles, and the muscles that com-prise the pelvic floor. B, The abdominal wall also includes a crossing relationship that affords increased sta-bility of the anterior and inferior aspect of our trunk below the umbilicus.

A B

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abdominis, internal oblique, external oblique, andrectus abdominis (Figure 3-45, A and B). These mus-cles form, connect into, and function via a fascial sys-tem referred to as the abdominal fascia. This fascialsystem forms an anterior and lateral strut that containsthe abdominal contents and operates as the base fromwhich the upper and lower extremities function. Theexternal oblique, internal oblique, and transversusabdominis attach into the abdominal fascia that sur-round the rectus abdominis muscle. The fibers of thetransversus abdominis muscle travel horizontally and

are best positioned to pull the abdominal contentsstraight back, thus effectively aligning the upper spineand shoulder girdle over the lumbopelvic region andhips (Figure 3-46). Indirectly, the rhomboids, pec-toralis major, serratus anterior, and femoral adductorscan be considered as part of the abdominal mecha-nism as well (see Figure 3-17, C ). The pectoralismajor’s linkage to the abdominal fascia and the serra-tus anterior’s linkage to the external oblique have beendescribed in previous sections of this chapter. Thesekey shoulder muscles are in fact an integral compo-nent of what we typically refer to as the “abdominalmechanism.” Exercises that can be used to strengthenthe abdominal wall, including those that incorporateshoulder girdle activity, are listed in Table 3-9 anddescribed in detail in Chapter 6.

SUMMARY

We have carefully described the clinically relevantaspects of the muscles associated with the shoulder gir-dle. The explanation of crossing relationships betweenvarious muscles gives you additional information abouthow a region with such great mobility simultaneouslyremains remarkably stable. In addition, we haveemphasized the relationships of muscles to each otherand their associated fascial networks. Strengtheningthe muscles that pull on these thick connective tissuesand performing exercises designed to hypertrophythose muscles that are contained within these fascialsystems represent primary goals of rehabilitation pro-grams designed to improve performance.

Appropriately maintaining the health of these tis-sues helps maintain the position of the scapula on thethorax and control the forces directed to the head ofthe humerus. When we lose the health of shouldergirdle muscles or the anterior strut of the abdominalcylinder, loads to the supporting tissues of the gleno-humeral joint are increased. It is logical to conclude


Rectusabdominis

Transversusabdominis

Figure 3-46. A sagittal plane view of the abdominalwall shows the fiber orientation of the transversus abdo-minis muscle and its importance in alignment of thespine and shoulder girdle with the lumbopelvic regionand hips.

Table 3-9. Exercises for the AbdominalMechanism

Standing high rows with thoracic cage flexion and pelvis tiltStanding rotary cable crossesGymnastic ball stabilizationKeeping abdominal wall toward beltline with concurrent upper

extremity and/or lower extremity load challengesSupine pullovers

DVD

DVD

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that initiating activities in the area predisposed toincreased joint pressures renders the tissues vulnera-ble to overload. The ability to maintain upright pos-ture is critical to secure scapular position and thesuccessful attenuation of stresses to the entire shoul-der complex. Strengthening the musculature of theshoulder girdle has to be complemented by a criticalassessment of the trunk and lower extremity strengthin order to provide a comprehensive approach torehabilitation in managing mechanical disorders ofthe shoulder complex. In Chapters 5 and 6 we willbuild on the clinical anatomy that has been discussedin the first four chapters as the foundation for theevaluation and treatment of mechanical disorders ofthe shoulder girdle.

REFERENCES

1. Arwert HJ, de Groot J, Van Woensel WW, et al:Electromyography of shoulder muscles in relation to forcedirection, J Shoulder Elbow Surg 6(4):360, 1997.

2. Blevins FT, Djurasovic M, Flatow EL, et al: Biology of the rota-tor cuff tendon, Orthop Clin North Am 28(1):31, 1997.

3. Blevins FT, Hayes WM, Warren RF: Rotator cuff injuries incontact athletics, Am J Sports Med 24:263, 1996.

4. Cain PR, Mutschler TA, Fu FH, et al: Anterior instability ofthe glenohumeral joint: a dynamic model, Am J Sports Med15:144, 1987.

5. Clark JM, Harryman DT II: Tendons, ligaments and capsule ofthe rotator cuff, J Bone Joint Surg Am 74(5):713, 1992.

6. DiGiovine NM, Jobe FW, Pink M, et al: An electromyographicanalysis of the upper extremity in pitching, J Shoulder ElbowSurg 1:15, 1992.

7. Elkhorn J, Arborelius UP, Hillered L, et al: Shoulder muscleEMG and resisting movement during diagonal exercisemovements resisted by weight and pulley circuit, Scand JRehabil Med 10:179, 1978.

8. Filo J, Furani J, De Freitas B: Electromyographic study of thetrapezius muscle in free movement of the shoulder, ClinNeurophysiol 31:93, 1991.

9. Frost P, Andersen JH, Lundorf E: Is supraspinatus pathology asdefined by magnetic resonance imaging associated with clin-ical signs of shoulder impingement? J Shoulder Elbow Surg 8(6): 565, 1999.

10. Fukuda H, Hamada K, Yamanaka K: Pathology and patho-genesis of bursal side rotator cuff tears viewed from end-block histologic sections, Clin Orthop 254:75, 1990.

11. Gartsman GM, Hammerman SM: Superior labrum, anteriorand posterior lesions, Clinics in Sports Med 19:115, 2000.

12. Giombini A, Rossi G, Pettrone FA, et al: Posterosuperior glenoidrim impingement as a cause of shoulder pain in top levelwater polo players, J Sports Med Phys Fitness 37:273, 1997.

13. Goldberg AL: Mechanism of work induced hypertrophy inskeletal muscle, Med Sci Sports 7:185, 1975.

14. Hawkins RJ, Bell RH, Lippitt SB: Atlas of shoulder surgery, St.Louis, 1996, Mosby.

15. Howell SM, Imobersteg AM, Seger DH, et al: Clarification ofthe role of the supraspinatus muscle in shoulder function,J Bone Joint Surg Am 68(A):398, 1986.

16. Itoi E, Bergland LJ, Grabowski JJ, et al: Tensile properties ofthe supraspinatus tendon, J Orthop Res 13:578, 1995.

17. Itoi E, Kido T, Sano A, et al: Which is more useful, the “full cantest” or the “empty can test” in detecting the torn supra-spinatus tendon? Am J Sports Med 27:65, 1999.

18. Itoi E, Kuechle DK, Newman SR, et al: Stabilizing function ofthe biceps in stable and unstable shoulders, J Bone Joint SurgAm 75(B):546, 1993.

19. Jensen BR, Jorgensen K, Huijing PA, et al: Soft tissue architec-ture and intramuscular pressure in the shoulder region,European J Morph 33:205, 1995.

20. Jobe FW, Moynes DR, Tibone JE, et al: An EMG analysis ofthe shoulder in pitching: a second report, Am J Sports Med12:218, 1984.

21. Johnson G, Bogduk N, Nowitzke A, et al: Anatomy and actionsof the trapezius muscle, Clin Biomech 9:44, 1994.

22. Kibler WB: The role of the scapula in athletic shoulder func-tion, Am J Sports Med 26:325-337, 1998.

23. Laumann U: Kinesiology of the shoulder joint. In Koelbel R,editor, Shoulder replacement. Berlin, 1987, Springer Verlag.

24. Lindman R, Eriksson A, Thornell LE: Fiber type composi-tion of the human female trapezius muscle: enzyme-histochemical characteristics, Am J Anat 190:385, 1991.

25. Lindman R, Eriksson A, Thornell LE: Fiber type compositionof the human male trapezius muscle: enzyme-histochemicalcharacteristics, Am J Anat 189:236, 1990.

26. Lizaur A, Marco L, Cebrian R: Acute dislocation of theacromioclavicular joint: traumatic anatomy and the impor-tance of the deltoid and trapezius, J Bone Joint Surg Am76(Br):602, 1994.

27. Logan GA, McKinney WC: The serape effect. In Kinesiology,Dubuque, Iowa, 1970, Wm C Brown.

28. Ludewig PM, Cook TM: Alterations in shoulder kinematicsand associated muscle activity in people with symptoms ofshoulder impingement, Phys Ther 80:276, 2000.

29. Mosely BJ, Jobe FW, Pink M, et al: EMG analysis of the scapu-lar muscles during a rehabilitation program, Am J Sports Med20:128, 1992.

30. Mottram SL: Dynamic stability of the scapula, Man Ther 2:123,1997.

31. Nakajima T, Rokuuma N, Hamada K, et al: Histologic and bio-mechanical considerations of the supraspinatus tendon: refer-ence to rotator cuff tearing, J Shoulder Elbow Surg 3:79, 1994.

32. Perry J: Biomechanics of the shoulder. In Bowe C, editor: Theshoulder, New York, 1988, Churchill Livingstone.



35. Reddy AS, Mohr KJ, Pink MM, et al: Electromyographicanalysis of the deltoid and rotator cuff in persons withsubacromial impingement, J Shoulder Elbow Surg 9(6):519,2000.

36. Saha AK: Dynamic stability of the glenohumeral joint, ActaOrthop Scand 42:491, 1971.

37. Scarpinato DF, Bramhall JP, Andrews JR: Arthroscopic man-agement of the throwing athlete’s shoulder: indications, tech-niques, and results, Clin Sports Med 10(4):913, 1991.


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38. Schmitt L, Snyder-Mackler L: Role of the scapular stabilizersin etiology and treatment of impingement syndrome,J Orthop Sports Phys Ther 29:31,1999.

39. Schwartz E, Warren RF, O’Brien SJ, et al: Posterior shoulderinstability, Orthop Clin North Am 18:409, 1987.

40. Sethi N, Wright R, Yamaguchi K: Disorders of the long headof the biceps tendon, J Shoulder Elbow Surg 8:6, 1999.

41. Solem-Bertoft E, Thuomas KA, Westerberg CE: The influenceof scapular retraction and protraction on the width of thesubacromial space: an MRI study, Clin Orthop and Rel Res296:99, 1993.

42. Sonnery-Cottet B, Edwards B, Noel E, et al: Results of arthro-scopic treatment of posterosuperior glenoid impingement intennis players, Am J Sports Med 30:227, 2002.

43. Soslowsky LJ, Carpenter JE, Bucchieri JS, et al: Biomechanicsof the rotator cuff, Orthop Clin North Am 28:1, 1997.

44. Tempelhof S, Rupp S, Seil R: Age-related prevalence of rota-tor cuff tears in asymptomatic shoulders, J Shoulder ElbowSurg 8:296, 1999.

45. Terry GC, Chopp TM: Functional anatomy of the shoulder,J Athletic Training 35(3):248, 2000.

46. Tibone JE, Elrod B, Jobe FW, et al: Surgical treatment of tearsof the rotator cuff in athletics, J Bone Joint Surg Am 68(A):887,1986.

47. Townsend H, Jobe FW, Pink M, et al: Electromyographic analy-sis of the glenohumeral muscles during a baseball rehabilita-tion program, 19[jb13](3):264,1991.

48. Uhthoff HK, Sano H: Pathology of failure of the rotator cufftendon, Orthopedic Clinics North Am 28:31, 1997.

49. Wadsworth DJS, Bullock-Saxton JE: Recruitment patterns ofthe scapular rotator muscle in freestyle swimmers with sub-acromial impingement, Int J Sports Med 18:618, 1997.

50. Wagner DB, Swienckowski JJ, Lennox JD: Painful subluxationof the acromioclavicular joint, Am J Sports Med 29:513, 2001.

51. Werner SL, Gill TJ, Murray TA, et al: Relationships betweenthrowing mechanics and shoulder distraction in professionalbaseball pitchers, Am J Sports Med 29:354, 2001.

52. Williams PL, Warwick R: Gray’s anatomy, ed 36, Philadelphia,1980, WB Saunders.

53. Yamaguchi K, Riew KD, Galatz LM, et al: Biceps function innormal and rotator cuff deficient shoulders: an electromyo-graphic analysis, Orthop Trans 18:191, 1994.

54. Yamanaka K, Matsumoto T: The joint side tear of the rotatorcuff: a follow-up study by arthrography, Clin Orthop 304:68,1994.


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INTRODUCTION

The often repeated words “the shoulder is built formobility rather than stability” can prevent us fromfully understanding how this remarkable complex ofarticulations simultaneously meets the demands ofmobility and stability. Indeed, it is perhaps moreinstructive to consider the shoulder complex asextraordinarily stable when it is viewed in the contextof the wide variety of motion possibilities and thenumerous torques and linear forces it is subjected to.

Shoulder girdle motion consists of a complex seriesof moving bony levers, motion of soft tissues over andbetween bursal interfaces, and an extraordinarily largenumber of combinations of muscle contractions in thespecific segments of muscles associated with thescapula, humerus, clavicle, radius, ulna, spine, andocciput. Bony levers forming these multiple articula-tions are under control of the neuromuscular system

and must instantaneously assume roles of stability andmobility on demand throughout even the simplest arcof motion.

Such an intricate mechanism presents the clinicianwith challenges during examination, evaluation, andselection of the most appropriate treatment interven-tions for the patient with shoulder pain or loss of func-tion related to mechanical problems of the shouldergirdle. The functional interplay of the multiple tissuesis closely aligned with the reality of shoulder disorders:most mechanical shoulder problems are not isolatedinjuries affecting only one structure within the shoul-der complex. Instead, most shoulder disorders,whether they occur from isolated injury, overuse syn-dromes, or simply as a result of the aging process,affect several tissues or structures of the shoulder gir-dle. In addition, the trunk and hip musculature play amajor role in the resting posture and movement pat-terns of the upper quarter, further increasing analready complex physiology.

In this chapter we detail the articulations of theshoulder girdle and consider the implications of struc-ture and function on selected aspects of the shoulderexamination and various interventions used in the man-agement of shoulder disorders. Our emphasis will beon the glenohumeral joint, acromioclavicular joint, andthe sternoclavicular joint and on two unique interfaces,

CHAPTER 4ARTICULATIONS OF THESHOULDER GIRDLE

91

Throughout this chapter you will find small circular icons marked“DVD” (see margin). These icons identify content that is coordi-nated with a video clip on the DVD accompanying this text. Formaximum learning benefit, go to the “Text Reference Section” onthe DVD and play the coordinated clip while reading the appropri-ate section of text. These clips expand on and reinforce the infor-mation presented in the text.

DVD

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92 ARTICULATIONS OF THE SHOULDER GIRDLE

the scapulothoracic interface and the suprahumeral-sub-acromial interface. That said, we approach these struc-tures within a framework of the full shoulder girdlemotion that also is dependent on motion of the cervicaland thoracic spine and the ultimate ability to stabilize thetrunk. For example, complete range of shoulder motionin elevation (lifting the arms completely overhead)requires a significant degree of cervical and thoracic spineextension. To hold a weight overhead, the spine must firstmove toward extension and then serve as a relatively stiffplatform in order to keep the weight stabilized overhead.Shoulder elevation with overpressure is an excellent wayto assess the extension and weight-bearing capacity of theapophyseal joints in the cervical and thoracic spines.

THE GLENOHUMERAL JOINT

The Head of the Humerus

The relationship of the head of the humerus to theglenoid fossa has often been likened to the “fit” of a golfball (head of the humerus) on a golf tee (glenoid fossa).Such a comparison emphasizes the disproportional con-tact relationship between the articular surfaces of thehumeral head and the glenoid fossa. It is a good analogybecause the actual contact relationship between thehead of the humerus and the glenoid fossa is relativelysmall. At any given moment of any motion, nearly 70%of the humeral head is not in contact with any part ofthe glenoid fossa. Despite this mismatch, the connectivetissue and neuromuscular stabilizing mechanisms pre-cisely maintain the head of the humerus within a 1 to2 mm variation throughout an arc of motion.39,49

Before more sophisticated analysis of glenohumeralmotion was possible, clinicians liberally applied thearthrokinematic rules for concave-convex joint sur-faces to the glenohumeral joint.61 Such rules implythat elevation of the humerus on the glenoid results inthe humeral head translating inferiorly on the glenoid.The clinical application of such a rule suggested usinginferior glide translations of the humeral head inorder to improve glenohumeral elevation (i.e., abduc-tion or flexion). Several studies have now shown thatthere is very little inferior glide of the humeral headon the glenoid during elevation.30,31,49 In fact, whenthe arm begins to elevate, the head of the humerusfirst translates superiorly approximately 1 to 3 mmand then remains relatively centered within the gle-noid fossa. This ability of the head of the humerus toremain centered on the glenoid is largely a function ofthe rotator cuff musculature, but other passive mech-

anisms that will be discussed later also come intoplay.21 Joint mobilization techniques remain excellenttreatment tools; however, use of these interventions isprimarily to introduce various translations and rotarystresses to the joint in order to maintain or improvegeneralized capsular mobility and enhance fluiddynamics. Used as a treatment intervention, suchtechniques result in improved motion in all ranges ofthe glenohumeral joint, rather than using a particulartranslation (glide) to improve physiological flexion,abduction, or rotation (see Chapter 6).

In addition to the head of the humerus, the proximalportion of the humerus features several key bony land-marks: the greater tuberosity with its three smooth andflat surfaces for muscle attachments (supraspinatus,

Greater tuberosityHumeralhead

Anatomicalneck

Bicipital groove

Surgical neckLesser tuberosity

Figure 4-1. Key structures of the proximal portion ofthe humerus include the humeral head, greater andlesser tuberosities, bicipital or intertubercular groove, theanatomical neck of the humerus, and the surgical neckof the humerus.

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ARTICULATIONS OF THE SHOULDER GIRDLE 93

infraspinatus, and teres minor); the lesser tuberosity witha flattened surface for the subscapularis attachment, thebicipital or intertubercular groove; and the anatomicaland surgical necks of the humerus (Figure 4-1).

The head of the humerus is not a complete sphere,and the smoothest part of its spherical head is coveredwith hyaline cartilage. This cartilage covered humeralhead faces medially and then is oriented upwardapproximately 130 to 150 degrees and backward(retroverted) approximately 26 to 31 degrees when thearm is by the side.34 It has also been suggested thathigh level overhead athletes demonstrate even greaterhumeral head retroversion on the dominant shoulderwhen compared with the nondominant side, implyingeven further bony adaptation as a result of prolongedcumulative stresses.10

The cartilage covering the head of the humerus isnot uniformly thick but instead is thicker in the centralregion of the humeral head and then becomes thinnerat the peripheral aspect of the head (Figure 4-2). Thisis exactly opposite to the relationship of the articularcartilage with the glenoid fossa, in which the cartilageis thicker at its periphery but thinner toward the cen-ter. The contribution that such a unique cartilaginousinterface makes to the stability of the glenohumeraljoint is discussed later in the Glenoid Labrum sectionof this chapter.

There are typically eight ossification centers withinthe humerus, but only three relate directly to the prox-imal aspect of the humerus. These three ossificationcenters are located in the head of the humerus, thegreater tuberosity, and the lesser tuberosity. While pre-liminary epiphyseal closure begins during childhood,it is generally not complete in these three centers until25 years of age (Figure 4-3).6 The medial end of thisupper epiphyseal line is intracapsular. The clinicianneeds to remember this especially important consider-ation when dealing with young athletes who presentwith shoulder trauma, or shoulder pain as a result ofmicrotrauma and overuse.

The Scapula

The triangular-shaped scapula typically overlies thesecond to seventh ribs and has three very distinct bonyprojections: the spine of the scapula, the continuation ofthis spine of the scapula as the acromion process, andthe coracoid process. The upwardly facing glenoid fossalies on the lateral aspect of the scapula. This fossa artic-ulates with the head of the humerus. In addition, twobony tubercles are associated with the glenoid cavity: the

supraglenoid tubercle and the infraglenoid tubercle(Figure 4-4, A).

There are numerous ossification centers in thescapula, including two in the coracoid process, three inthe acromion process, one in the scapula body, and onein the rim of the glenoid cavity. The ossification centersof the scapula are typically united between the ages of 20and 24 years of age. The three ossification centers in theacromion are united by 22 years of age, but if they fail tounite, a condition referred to as osacromiale results. Thiscondition is often associated with rotator cuff degenera-tion.46 The clinician needs to always keep the presence ofthese ossification centers in mind when evaluating chil-dren, adolescents, and young adults for shoulder pain.

The Glenoid Cavity

The total articular surface of the glenoid fossa is lessthan a third of the total articular surface of thehumeral head (see Figure 4-2). Its relatively small fossafaces backward approximately 4 to 12 degrees relativeto the plane of the scapula. Since the plane of thescapula is approximately 30 to 40 degrees anterior tothe coronal plane of the body, the glenoid fossa is actu-ally directly facing the posteriorly facing humeral head.

Because the scapula is a relatively flat bone, a scapu-lar “plane” can be described based on the position ofthe scapula as it moves over the thorax (Figure 4-4, B).The reader needs to be able to visualize this planebecause the position of the scapula on the thorax ulti-mately results in the glenoid fossa having a variety ofpossible orientations relative to the plane of the body.For example, when the shoulder girdle is in completeretraction, the scapular plane more closely parallels thecoronal plane of the body. When the shoulder is fullyprotracted, however, the scapular plane more closelyparallels the sagittal plane of the body.

The importance of being able to visualize the planeof the scapula is related to the clinician’s ability toanalyze forces of the humerus on the glenoid andbetween the humeral head and the suprahumeraldome with various exercises. The suprahumeral domeconsists of the undersurface of the acromion, cora-coacromial ligament, coracoid process, and the con-joint tendon of the coracobrachialis and short head ofthe biceps brachii. Note that with the scapula pro-tracted and the glenohumeral joint in flexion, there isa compressive load of the humerus on the glenoidwhen a force is applied through the long axis of thehumerus. The same force applied through the longaxis of the humerus with the same glenohumeral

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Glenoidfossa

Articular cartilage Humeral head

130� –150�

26� –31�

Figure 4-2. A, The head of the humerus is angled upward 130 to 150 degrees, and B, backward26 to 31 degrees. C, The articular cartilage, as seen in the superior transverse section, that covers thehead of the humerus is thicker in its central region and thinner in the periphery.

A B

C

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flexion but with the scapula retracted results in agreater posterior shear force between the humerusand scapula and markedly less compression betweenthe humeral head and glenoid.

Consider the application of these mechanics toshoulder girdle exercises. When we do a wall push-upor a floor push-up, the position of the scapula ulti-mately dictates what the joint reactive force will be atthe glenohumeral joint. Weak scapular protractorsresult in the scapula being positioned in the coronalplane of the body with a significant glenohumeralshear force occurring with the exercise. In the sameexercise, strong scapular protractors would align thescapula more closely to the sagittal plane and result inmore glenohumeral joint compression and less shearof the humeral head on the glenoid. The same type of

analysis can be performed with open kinetic chainexercises such as shoulder elevation. When performedin three different scapular planes—along the sagittalplane of the body, the frontal plane of the body, andmidway between the two—differences in the gleno-humeral joint reactive forces result.

The clinician working with a patient with anymechanical shoulder disorder must be cognizant ofthose scapular and humeral positions that result inincreased glenohumeral shear or compression. This istrue when applying passive joint mobilization tech-niques, as well as when designing an exercise prescrip-tion for resistance exercises for the shoulder. Forexample, we typically recommend that shoulder eleva-tion exercises, especially when using free weights orpulleys, be performed in a plane midway between thecoronal and sagittal planes. This is the approximateplane of the scapula as it rests over the thorax, oftenreferred to as the scaption plane. Careful observation orpalpation of the scapular motion during the exercisecan help verify that plane. Furthermore, it is essentialthat the clinician note the quality and the quantity ofscapular motion during any resisted shoulder elevationexercises. We typically emphasize the scapular pro-traction, rotation, and elevation components of anylateral or forward arm raise exercises. Ignoring thisfundamental shoulder exercise concept—the scapulamoving smoothly and strongly into protraction,upward rotation, and elevation during forward or lat-eral arm raise exercises—results in excessive compres-sion of the soft tissues lying in the suprahumeral space,which we will discuss in detail later. Ludewig andCook have demonstrated that decreased serratus ante-rior muscle activity is very common in patients withimpingement syndrome and note that attention to theactions of this key muscle is essential in shoulder reha-bilitation programs.37

It is equally important to analyze the scapular posi-tion when performing closed kinetic chain exercises.Most importantly, the clinician must take great care indeveloping a closed kinetic chain exercise prescriptionfor shoulder strengthening because 1) the gleno-humeral joint is not designed to be a weight-bearingjoint, and 2) shear loads may be poorly toleratedbecause of limitations of the specialized connective tis-sue restraints. The complexity of these mechanisms isone of the reasons why designing an exercise programfor the compromised shoulder joint is so difficult.

The above descriptions reinforce the fact that theglenohumeral joint is a multiaxial joint, which is capa-ble of movement in all planes. Only a small portion of


HeadGreatertuberosity

Lessertuberosity

Figure 4-3. A cross section of the right humerus showsthe three ossification centers associated with the proxi-mal aspect of the humerus (head, and greater and lessertuberosity), which typically fuse to form one larger ossi-fication center by the sixth year of life.

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the head of the humerus is in contact with the glenoidfossa at any given moment; additionally there are veryfew positions in which the head of the humerusbecomes completely congruent with the surface of theglenoid fossa. Maximal congruency between the bonypartners of a synovial joint is referred to as the close-packed position of the joint, and the position of maxi-mal congruency for the glenohumeral joint occurswhen the humerus is abducted and externally rotated.As expected, this position of abduction and externalrotation is also the position in which the highestdegree of load-bearing articular pressure between thehead of the humerus and the glenoid fossa occurs.8This position also places the inferior aspect of the joint

capsule and the inferior glenohumeral ligament undersignificant tension, and it is a very vulnerable positionfor dislocation, subluxation, or excessive strain ofthese specialized connective tissues supporting thejoint. In contrast, the loose-packed position of thejoint, a position in which there is the least resistance toany translation because of capsular and ligamentouslaxity, is a position in which the humerus is placed inapproximately the plane of the scapula, namely, 55degrees abduction and 30 degrees horizontaladduction.

Applying this understanding of the bony levers thatform the glenohumeral joint, we can now detail sev-eral of the support structures that help maintain the


Coracoid process

Supraglenoid tubercle

Infraglenoidtubercle

Spine of scapula

Acromion

Figure 4-4. A, This view of the lateral aspect of the scapula demonstrates the position of thesupraglenoid and infraglenoid tubercles relative to the glenoid fossa and the key scapular processes:the spine of the scapula, acromion process, and coracoid process. B, This view shows the plane ofthe scapula.

A B

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contact relationship between the humerus and the gle-noid. Several key specialized connective tissue struc-tures are intimately associated with the bony leversconstituting the glenohumeral joint, including the gle-noid labrum, long head of the biceps tendon, jointcapsule, synovial lining, capsular ligaments, bursalinterfaces, and the rotator cuff tendons. The interplaybetween each of these structures is critical to normalshoulder function, so we will examine several impor-tant clinical points related to these structures.

Specialized Connective TissueStructures Associated With the Glenohumeral Joint

The Glenoid Labrum

The triangular- to round-shaped glenoid labrum isattached around the margins of the glenoid rim and isa composite of fibrous and cartilaginous material.9The structure of the labrum is such that the thickerportion of labrum is attached to the glenoid rim,whereas the thinner portion comprises its free edge.The superior aspect of the labrum or “12 o’clock posi-tion” on the glenoid face generally has a “looser”attachment to the glenoid than the inferior aspect ofthe labrum or “6 o’clock position” and is continuouswith the long head of the biceps tendon (Figure 4-5).The inferior labrum is also more substantive and hasmore bulk than the superior aspect.23 As a result of itsperipherally placed position on the glenoid, thelabrum effectively deepens the glenoid socket to adepth ranging from 5 mm to 10 mm.29

The labrum plays several important roles in shoul-der mechanics, but the primary role is its contributionto stability of the glenohumeral joint. As evidence ofits contribution to stability, it is estimated that a torn ordeficient labrum results in approximately 20% moretranslatory movement of the humeral head on the gle-noid than when the labrum is intact. This clearlyresults in instability between the humeral head andglenoid.35

How do the hyaline cartilage coverings of the gle-noid and humerus work in concert with the labrum tocontribute to glenohumeral stability? The combina-tion of a thicker hyaline cartilage in the periphery ofthe glenoid rim in conjunction with the added glenoidrim elevation afforded by the glenoid labrum results ina more closely matching radius of curvature of thehead of the humerus with the radius of curvature of

the glenoid. The fossa is functionally deepened by thisarrangement. Thus one contribution to stability issimply the increase in the concavity of the glenoidfossa via deformation of the articular cartilage and themechanics of the labrum.

The thicker cartilage at the periphery, plus thefibrocartilaginous glenoid labrum, contributes to themechanical stability of the glenohumeral joint in moreways than simply increasing the depth of the fossa. Aregion in which there is a thick hyaline cartilage “cush-ion” typically has greater flex or ability to deform (i.e.,that region can be more easily compressed and thencan spring back to its original shape). The periphery ofthe glenoid rim exhibits this particular quality ofdeformability. At the periphery of the glenoid rim thearticular cartilage becomes thicker as it blends into thefibrocartilaginous labrum. The combination of thethicker cartilage and fibrous labrum leads to increasedflexibility or deformability at the periphery of the gle-noid rim, resulting in the humeral head being “sealed”when pressed into the glenoid (Figure 4-6). The com-pression of the humeral head into the glenoid fossaultimately creates a functional seal between theperipheral rim of the cartilaginous glenoid and the


Glenoidlabrum

Bicepstendon

Figure 4-5. The glenoid labrum is triangular in crosssection and is continuous at its superior surface with thelong head of the biceps tendon.

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humeral head, much like the outer rim of a toy dartconstructed with flexible rubber on its periphery(glenoid) creates a “seal” that would allow the dart tostick to a glass ball (head of humerus).

A slightly negative pressure also is present within thejoint cavity. Although the joint surfaces are wet (coatedwith synovial fluid), very little fluid is actually present inthe joint. This is because of the osmotic action of thesynoviocytes within the joint synovium. As long as thesynovial osmotic pressure (ability of the synoviocytes toremove fluid from the joint environs) remains greaterthan the osmotic pressure of the colloids withinthe synovial fluid, a “negative” pressure exists within thejoint cavity and the joint is better sealed. This stabiliz-ing or sealing phenomenon brought about by a squeez-ing together of the wet surfaces of the head of thehumerus and the glenoid is further enhanced via con-traction of the rotator cuff musculature, which illus-trates one of their many roles in contributing to thestability of the glenohumeral joint.

If the joint has an increase in the volume of jointfluid, which might occur as a result of joint effusion orhemarthrosis, a functional seal between the humeral

head and glenoid cannot be maintained, in partbecause of increased joint volume and in part becauseof a difference in osmotic pressure. The osmotic pres-sure in the joint cavity exceeds the osmotic pressure inthe synovium. This scenario can create an abnormalcontact relationship of the humeral head and the gle-noid, resulting in joint instability.

When you recognize these labral, cartilage, andjoint mechanics, you will more fully understand howinstability of the glenohumeral joint might result fromdefects in the glenoid labrum or from degenerativejoint disease associated with the humeral head or gle-noid fossa. Although there are several causes of gleno-humeral joint instability (Table 4-1), labral or humeralhead defects are important factors because when pres-ent, they result in the joint losing its ability to maintainthe essential functional seal created within the jointcavity. Thus the structural integrity of the very struc-tures that must create this type of seal has beencompromised.

Many tests have been described for assessing insta-bility of the glenohumeral joint. Regardless of thename of the test, the intent remains the same: to trans-late the head of the humerus parallel to the glenoidsurface through the application of shear forces invarying degrees of glenohumeral positioning and withthe glenohumeral joint placed in high risk positions.The examiner assesses the quantity, quality, and endfeel of the translation, all the while noting the effect onthe patient’s familiar symptoms. Instability is a clinicaldiagnosis and should not be confused with generalizedjoint laxity. Although individuals with excessive jointlaxity are at risk for instability, the clinical diagnosistypically is made when function is impaired or painresults. Table 4-2 lists clinical tests and evaluation find-ings that lead us to suspect glenohumeral instability.


Glenoid labrum

Articular cartilage

Figure 4-6. The sealing phenomenon of the gleno-humeral joint capsule results from the thicker articularcartilage and the fibrous glenoid labrum, which give theperiphery of the glenoid rim greater flexibility. As thehead of the humerus is compressed into the glenoid, itsease of deformability on the peripheral aspect of the gle-noid allows the creation of a negative pressure within theglenohumeral joint, thereby contributing to gleno-humeral stability.

Table 4-1. Anatomical ChangesContributing to the Loss of

Glenohumeral Stability

1. Defects in the glenoid labrum2. Irregular, roughened surface of humeral head (DJD)3. Increased fluid volume within joint cavity4. Defect in joint capsule5. Loss of compliance of joint capsule or glenohumeral

ligaments

DJD, Degenerative joint disease.

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Labral Defects

Labral defects can occur along any portion of theglenoid, but two in particular have received a greatdeal of clinical attention: the Bankart lesion and theSLAP (superior labral anterior to posterior) lesion.The Bankart lesion is a detachment of the labrumfrom the anterior glenoid rim (Figure 4-7, A). Forcedabduction and external rotation of the glenohumeraljoint at endrange loads the anterior-inferior aspect ofthe joint capsule and the anterior labrum and is thetypical position in which the detachment of thelabrum and stretch or tear of the inferior gleno-humeral ligament complex might occur, resulting inthe Bankart lesion.

Trauma, typically forced abduction and externalrotation or a force over the back of the humerus driv-ing it anteriorly against the anterior capsular wall, canresult in glenohumeral subluxation or dislocation in

addition to a Bankart lesion. A tear of the anteriorlabrum and capsule renders the joint unstable as aresult of this trauma. This type of injury is easily rec-ognized and has resulted in one of the more commonclassifications of glenohumeral instability, referred toby the acronym TUBS (Traumatic Unilateral BankartSurgery). TUBS means the mechanism of injury wastrauma to one shoulder (unilateral), resulting in aBankart lesion that most likely requires surgery torepair the labrum and avulsed capsular complex inorder to restore joint stability (see Chapter 5).

Cumulative stresses may also place excessive stresson this same anterior capsule-labrum complex. Agood example is throwing. During the late cockingphase of throwing, the shoulder is in maximal externalrotation while the body is moving forward. With thearm going “backward” in external rotation and thebody simultaneously coming forward, there is a con-siderable buildup of tensile stress to the anterior cap-sule and labrum that renders the region susceptible todamage and a resultant Bankart lesion. Such cumula-tive stress can result in a continuum of tissue damagein the Bankart lesion from simple fraying of thelabrum to detachment and substantial fraying ofthe labrum.22

We want to emphasize the importance of thestrength and endurance of the scapular muscles inhelping to prevent Bankart lesions now that the mech-anisms of injury leading to Bankart lesions are under-stood (Figure 4-7, B and C). If the scapular stabilizerscannot position the scapula in the scaption plane, thepotential for greater stress to the anterior capsule-labrum complex increases. When the scapula “lags”behind in the frontal plane during the cocking phaseof throwing, it results in the anterior capsule andlabrum being placed under a significant tensile load.In contrast, scapular muscle control that places andhelps maintain the scapula closer to the scaption planewill minimize the stress to the anterior capsule-labrumcomplex.

The detachment of the superior labrum–long headof the biceps complex is referred to as a SLAP lesion(Figure 4-8). There are several different mechanicalderangements of the long head of the biceps tendonthat have been described and range from a minoravulsion of only a few fibers to complete separation ofthe biceps tendon and labrum away from the glenoidso that it resembles the classic bucket handle lesion ofthe knee joint.12

The SLAP lesion typically occurs with shouldertrauma that might occur with glenohumeral


Table 4-2. Tests and ExaminationFindings Pointing TowardGlenohumeral Instability

1. Positive sulcus sign• Excessive space noted at suprahumeral region as a result

of inferior translation of humerus• Can be assessed for in a neutral position and at 90 degrees

abduction2. Positive drawer test

• Excessive anterior or posterior translation of humeral head on glenoid

• Can also be performed with shoulder in varying ranges ofelevation or rotation

3. Positive load and shift test• Compression of head of humerus into glenoid and then

anterior-posterior translation assessed4. Positive apprehension test (crank test)

• Shoulder is positioned at 90 degrees abduction and slowlyexternally rotated

5. Positive relocation test• Apprehension position is repeated but with examiner

stabilizing anterior aspect of joint6. “Clunk” test

• Full overhead flexion and caudal glide from which position the examiner performs a circumduction motionof the humerus, trying to cause a clunk of the humeralhead over anterior labrum

7. Anterior glenoid rim tender with palpation8. Past frequency of dislocations or reductions9. Does arm transiently “go dead”?

10. Are there associated impingement phenomena?11. What is the generalized connective tissue “laxity” of the

patient?

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Bankartlesion

Figure 4-7. A, This view shows the anatomical location of the Bankart lesion. B and C, Visualizethe stress to the anterior wall of the glenohumeral joint capsule and capsular ligaments during thecocking phase of throwing. In addition, the position of the scapula (protracted versus retracted) alsodetermines whether there is a shear stress or compression stress between the humerus and the glenoid.

B

A

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dislocations or subluxations, with falls on the out-stretched arm, and in throwing sports and overheadwork.55 These mechanisms of injury result in severaldifferent loading patterns to the labrum–biceps tendoncomplex. The fall on the outstretched hand drives aforce through the long axis of the humerus and ulti-mately compresses the soft tissues located within thesuprahumeral space into the undersurface of the cora-coacromial arch. This not only excessively compressesthe rotator cuff tendons but also the superiorly posi-tioned glenoid labrum–biceps tendon complex.54

Traction through the long head of the biceps ten-don associated with the repetitive motion and deceler-ation requirements of throwing or racquet sports mayalso result in avulsion of the labrum–biceps tendoncomplex. The throwing motion is especially complexsince considerable stress is applied to the biceps ten-don during the deceleration phase of the throwingmotion. During this phase of the throwing motion, theelbow is rapidly extending and the biceps is contract-ing vigorously to control the rate and extent of theelbow extension (Figure 4-9). The tension increase atthe attachment of the biceps tendon to the labrum isdue to the eccentric contraction of the biceps, as well

as the extension motion of the elbow and arm.Another example of increased tension is the rapidoverload to the elbow flexors, such as in catching afalling object or in rapid jerking motions of lifting.

The superior aspect of the glenoid labrum (theregion on the glenoid face between 11and 3 o’clock) iseven more complex because the labrum–long head ofthe biceps tendon complex is also intimately related tothe superior and middle glenohumeral ligaments (seeFigure 4-8). The anatomical configurations of thisconfluence of highly specialized connective tissue maytake several different variations, and therefore the linebetween a pathological lesion in this region and a nor-mal variant of the anatomy remains unclear. The clin-ical picture is further complicated because thesuperior portion of the glenoid labrum is typically lessvascular than the inferior aspect. Thus there may belimitations to the healing capabilities of the superiorregion in pathological states.12


SLAP lesion

Figure 4-8. Note the close relationship of the longhead of the biceps tendon and glenohumeral ligamentsin this superior aspect of the glenoid labrum. This is alsothe location of the SLAP lesion.

CFigure 4-7, cont’d

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A clinician should suspect glenohumeral instabilitywhenever the patient’s history is suggestive of a defectto any aspect of the glenoid labrum. A few endrangemovement tests of the glenohumeral joint have beendescribed in this chapter, but labral defects present aneven more formidable rehabilitation challenge.Although labral lesions are difficult to detect with non-invasive tests during the physical examination, thereare some symptoms and signs that can lead us to sus-pect that the labrum is involved. These include sensa-tions of “catching” or “clicking” during specificrepetitive shoulder movements and the presence oftenderness to palpation when the soft tissues over theanterior aspect of the glenoid rim are compressed bythe examiner’s fingers and moved over the anteriorglenoid rim (see Chapter 5).

The Joint Capsule and SynovialMembrane

A fibrous capsule lined with a synovial membraneenvelops the glenohumeral joint. It is similar to mostsynovial linings of the joints, and its cells within thesynovium synthesize and maintain the major compo-nents of the joint fluid. The remarkable feature of thejoint fluid is that it adheres to the articular cartilage,enhancing joint lubrication, while simultaneously thefluid-lined articular cartilage surfaces “stick” to eachother. This is an important factor that contributes toglenohumeral joint stability. Disease processes such asrheumatoid arthritis, in which the viscosity of the syno-vial fluid is altered or where the ability of the synovialfluid to adhere to cartilage is diminished, can result in



Figure 4-9. The decelerationphase of the throwing motion putssignificant stress to the long head ofthe biceps tendon because thebiceps muscle is contracting vigor-ously to control the rate and extentof elbow extension.

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joint instability. This is because of the decrease in theadhesive and cohesive properties of the synovial fluid.In addition, the osmotic pressure equilibrium betweenjoint fluid and the synovial lining is altered.

The joint capsule itself is fairly thin and redundantand makes a minimal contribution to static gleno-humeral joint stability. Medially, the capsule is attachedto the complete rim of the glenoid just outside the gle-noid labrum. Laterally, the joint capsule is attached tothe anatomical neck of the humerus. Most of the con-nective tissue fibers of the capsule run horizontally, butclose inspection of the capsule reveals oblique andtransverse fibers as well. One of the unique features ofthe joint capsule is its laxity. Not only can the scapulaand humerus be moved relative to each other, but whenthe glenohumeral joint is abducted so as to relax thesuperior portion of the capsule, the joint surfaces canalso be slightly “decompressed” as a result of distractiveforce. When the arm is at the side, the inferior part ofthe capsule is typically lax with a characteristic redun-dant “fold.” This fold is taken out of the joint capsule asthe arm is elevated, and the inferior aspect of the jointcapsule becomes increasingly taut.

Another unique feature of the shoulder joint capsuleis the additional support it receives on its outer andinner aspects. The external aspect of the fibrous cap-sule is supported by the four rotator cuff tendons (seeChapter 3): the supraspinatus on the capsule’s superiorsurface, the infraspinatus and teres minor on the poste-rior surface, and the subscapularis on the anterior sur-face (Figure 4-10). Although not considered part of therotator cuff, the long head of the triceps supports theinferior aspect of the joint capsule, particularly whenthe humerus is in a position of forward elevation.

The relationship of the rotator cuff tendons to thejoint capsule is important because the cuff tendonshave well defined bony attachments to the humeraltuberosities and completely blending with the fibrouscapsule of the glenohumeral joint (see Figure 4-10). Asnoted in Chapter 3, contraction of the rotator cuffmuscles not only results in movement of the humeruson the scapula but also contributes to increasing ten-sion to the glenohumeral joint capsule. The increasein capsular tension results in enhanced stability at theglenohumeral joint through a type of dynamic sup-port to glenohumeral stability as a result of increasedmuscle action augmenting the connective tissue stiff-ness of the joint capsule.

This relationship of the rotator cuff tendons to thejoint capsule is especially important to consider in theexamination of the patient with limited range of

motion of the glenohumeral joint. Unless the muscula-ture is fully relaxed, passive motion of the humerus onthe glenoid will present as limited glenohumeralmotion. In addition to considering that the capsule itselfmight have been subjected to adaptive shortening orhas fibrous adhesions, it is also anatomically and neuro-physiologically plausible to consider that an increasedresting tension or protective guarding of the rotator cuffmusculature, in particular the infraspinatus and teresminor, may be contributing to limited motion.

For example, a limitation in glenohumeral internalrotation may be due to tightness of the posterior cap-sule but might also be a result of increased restingstate of muscle contraction of the infraspinatus andteres minor muscles in order to minimize compressionwithin the suprahumeral space. Figure 4-11 demon-strates a patient with limited internal rotation on oneside compared with the other. Note that because ofthe arm position, the internal rotation motion itselfresults in increased compression of the humeral headinto the coracoacromial arch. It is this resultant com-pression to previously irritated or swollen tissues(impingement syndrome) that may trigger the imme-diate protective guarding of the shoulder external



SupraspinatusGlenohumeral

joint capsule

Infra-spinatus

Teresminor

Subscapularis

Figure 4-10. A lateral view of the glenohumeral jointcapsule shows the relationship of the rotator cuff ten-dons to the capsule’s external aspect.

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rotators and minimize any further motion in the direc-tion of internal rotation.

The openings found within the fibrous capsule itselfare the final unique anatomical features of the joint cap-sule. Typically there are two openings, but occasionallythree may be seen. One opening is present at the upperregion of the intertubercular (bicipital) groove. Thisopening allows the long head of the biceps tendon totravel along the superior head of the humerus in itscourse to reach the supraglenoid tubercle and the gle-noid labrum of the scapula. At the region in which thisopening appears, the fibrous capsule becomes increas-ingly thick and the fibers of the capsule contribute to theintricate framework of connective tissues that helpsecure the long head of the biceps in the intertubercular

groove (see Chapter 3). The second opening of thefibrous capsule is anteriorly placed, which permits com-munication of the synovial membranes of the gleno-humeral joint capsule with the synovial bursal sacforming the subscapular bursa. The subscapular bursalies deep to the subscapularis tendon as it crosses the gle-noid neck and travels toward the lesser tuberosity (Figure4-12). A third opening is often found posteriorly in whichthe synovial membrane of the joint capsule communi-cates with the infraspinatus bursa in the same way com-munication with the subscapularis bursa occurs on theanterior aspect of the joint.

The Capsular Ligaments

In addition to the external reinforcement of thecapsule by the rotator cuff tendons, further support isprovided on the inner surface of the joint capsule bythree ligaments: the superior, middle, and inferior


Opening for communicationwith subscapular bursa


Figure 4-12. The anterior aspect of the capsuledemonstrates the two constant openings of the fibrousjoint capsule: the opening for the long head of the bicepsand the opening for the communication with the sub-scapular bursa.

Figure 4-11. The patient has been asked to internallyrotate both shoulders from the starting position of 90degrees abduction. The right shoulder demonstrates lim-ited internal rotation, which might be caused by two dif-ferent reasons: a tight posterior capsule or protectiveguarding of the infraspinatus and teres minor as theycontract to minimize further compression of the head ofthe humerus into the coracoacromial arch in the patientwith a shoulder impingement lesion.

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glenohumeral ligaments. Because these ligaments arefeatured primarily on the inner aspect of the anteriorwall of the joint capsule, the anterior aspect of thejoint capsule is noticeably thicker than the posteriorpart of the capsule.

The superior glenohumeral ligament (Figure 4-13)is thin and slender. It is attached to the glenoid rimimmediately adjacent to the long head of the bicepstendon and travels toward the humerus paralleling thelong head of the biceps, attaching to the upper aspectof the lesser tuberosity. The middle glenohumeral lig-ament lies just inferior to the superior glenohumeralligament and attaches to the lesser tubercle just belowthe subscapularis muscle attachment.

The largest and most developed of these ligaments isthe inferior glenohumeral ligament. Its breadth is suchthat it can be studied as three functional subparts: ananterior component (anterior-inferior glenohumeralligament), an axillary component (axillary-inferiorglenohumeral ligament), and a posterior component(posterior-inferior glenohumeral ligament).47 Theplacement of this ligament on the glenoid is best

described by viewing the glenoid as the face of a clock.The extent of this ligament is such that the attachmentsof the three components of the inferior glenohumeralligament span an area from approximately 3 to 8o’clock. Such an arrangement of the three componentsresults in the ligament serving as a sling or “hammock”for the head of the humerus (see Figure 4-13). Whenour arm is at our side, the inferior glenohumeral liga-ment serves to support the head of the humerus. Whenour arm is abducted and externally rotated, however,the major components of the inferior glenohumeral lig-ament are positioned anterior to the head of thehumerus and help stabilize it against anterior transla-tion of the humeral head on the glenoid (Figure 4-14).If the applied force of abduction and external rotationexceeds the connective tissue tolerance of the inferior


Superiorglenohumeralligament

Middleglenohumeralligament

Anterior band of theinferior glenohumeralligament complex

Posterior bandof the inferiorglenohumeral

ligamentcomplex

Figure 4-13. The superior, middle, and inferior gleno-humeral ligaments reinforce the inner wall of the jointcapsule. The superior glenohumeral ligament is thesmallest of the three ligaments, whereas the inferiorglenohumeral ligament is the largest.

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ER

ABD

Figure 4-14. The inferior glenohumeral ligament liesinferior to the axis of the joint in anatomical position,and the head of the humerus lies on it “hammock”style. When the humerus is abducted (ABD) and exter-nally rotated (ER), the ligament is pulled upward andbecomes positioned anteriorly to the joint, thus servingas a major restraining force for anterior translation ofthe humeral head.

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glenohumeral ligament, the connective tissue fibers aretorn or stretched. The lack of a restraining force toanterior translation by the inferior glenohumeral liga-ment potentially results in instability of the gleno-humeral joint, especially when the arms are lifted awayfrom the body.

The final capsular ligament that we discuss in this sec-tion is the coracohumeral ligament. Unlike the gleno-humeral ligaments that lie on the inner wall of theshoulder joint capsule, the coracohumeral ligament lieson the external surface of the fibrous capsule. As thename implies, it extends from the coracoid process to thegreater tuberosity. This ligament is located in a region ofthe superior joint capsule known as the rotator interval.The rotator interval is a space bound by the anteriorborder of the supraspinatus muscle and the superiorborder of the subscapularis muscle (Figure 4-15).Therefore, from superficial to deep, the rotator intervalis occupied by the coracohumeral ligament, the jointcapsule, the superior glenohumeral ligament, and thelong head of the biceps tendon.

Pathology: Adhesive Capsulitis, or “Frozen Shoulder”

Shoulder stiffness, and the pain and disabilityresulting from such stiffness, can be caused by a vari-ety of reasons. Here we discuss those elements ofshoulder stiffness that appear related to changes inthe joint capsule or the glenohumeral ligaments. Theterm adhesive capsulitis was first noted by Neviaser.43

He described a clinical condition of limited shouldermovement that appeared to result from an inflam-matory process, which changed the compliance ofthe joint capsule connective tissues. This sequenceresulted in fibrosis and thickening of the capsule andligaments. Motion limitation associated with suchdiffuse connective tissue changes results in all gleno-humeral motions being affected rather than a limita-tion of motion in only one direction.

The pathogenesis of the stiff glenohumeral joint(adhesive capsulitis, or “frozen shoulder”) is mostlikely a cascade of cellular events that begins with aninflammatory reaction. Such inflammatory eventsare marked by increased vascularity and the presenceof inflammatory cells in the synovium.25 The synovi-tis results in a fibroblastic response within the adja-cent capsule. The insult initiating inflammation istypically unknown, although microtrauma andmacrotrauma or autoimmune reactions associatedwith the cells or vasculature of the joint capsule andsynovial lining may be contributing factors. Theresult of a chronic inflammatory process can befibrosis, which results in thickening of the normallythin and redundant capsule with associated contrac-tures of the collagen fibers.44

Cyriax proposed that inflammation of the jointcapsule and a resultant limitation of motion fol-lowed a predictable pattern of limitation.11 Hecalled the proportional limitation of motion “thecapsular pattern” and suggested that all synovialjoints have a predictable proportional loss of motionwhen the joint capsule is the primary structureinvolved. The capsular pattern for the shoulder isdescribed as a motion pattern in which the externalrotation is the most limited motion, followed byglenohumeral (not total shoulder) abduction, andinternal rotation as the least limited motion. Theexaminer will usually assess the patient for a capsu-lar pattern when examining the shoulder usingpassive range-of-motion maneuvers. It is essentialthat the tests applied are truly passive in nature. Ifthere is muscle guarding or the patient actively


Rotatorinterval

Figure 4-15. The rotator interval is the portion of thecapsule in which there is no reinforcement by the rotatorcuff tendons. It lies between the subscapularis muscleand the supraspinatus muscle. The coracohumeral liga-ment supports the capsule in this space.

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assists with the motion, a true assessment of thenoncontractile tissues, such as the joint capsule, can-not occur. Although many patients with a stiff andpainful shoulder may not have these exact propor-tions of limitations, it is quite remarkable how com-mon it is for external rotation to be exquisitelypainful and limited and a passive external rotationmaneuver to quickly elicit protective muscle spasm.This is a good indication that the joint capsule isinvolved in the syndrome.

Asymmetric tightness of the capsule, whichimplies that only one region of the capsule is tightrather than the complete capsule, alters the mechan-ics of the humerus as it moves under the coracoacro-mial arch by forcing it to translate away from itscentral point on the glenoid.26,38 Matsen and col-leagues have used the term obligate translation todescribe the phenomenon of the tight capsule push-ing on the humerus, which shifts it off its centralposition on the glenoid (Figure 4-16).38 When flexingthe shoulder with a tight posterior joint capsule, thehumeral head is driven up and forward into theundersurface of the anterior coracoacromial arch,compressing the soft tissues located in this region.

THE SUPRAHUMERAL-SUBACROMIAL INTERFACE

The interface between the superior aspect of thehumerus and the inferior aspect of the acromion haslong captured the attention of clinicians as ananatomical region from which numerous shoulder dis-orders may emanate. The inferior bony border of theregion is the convex head of the humerus, particularlythe greater tuberosity, whereas the concave undersur-face of the acromion and coracoid process serve as thesuperior border. The complete extent of the concavearch is even more complex because it is formed by acombination of bony tissue and other specialized con-nective tissues. From posterior to anterior, the arch isformed by the acromion, acromion process, cora-coacromial ligament, and the conjoint tendons of theshort head of the biceps and coracobrachialis muscles(Figure 4-17).

The convex partner of this interface is trulyunique. It consists of the head of the humerus andattached rotator cuff tendons, which are intimatelyblended with the glenohumeral joint capsule. Thesubacromial bursa lies at the interface between the


+

+

Posteriorcapsule

Posteriorcapsule

(squeezing)

Figure 4-16. The concept ofobligate translation is exhibitedwhen tightness of the posteriorcapsule results in the humerusbeing driven superiorly and ante-riorly into the coracoacromialarch, thus compressing the soft tis-sues in this interface.

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rotator cuff tendons and the undersurface of the con-cave arch (Figure 4-18). The space between the con-vex humeral head and the arch that is formed by theacromion, coracoacromial ligament, coracoid, andconjoint tendons is approximately the thickness of therotator cuff tendons. Attrition (thinning) of the rota-tor cuff tendons results in a decrease in the height ofthe subacromial space.

Previously we described the motion between thehumerus and glenoid fossa. Note, however, thatbecause of the attachment of the rotator cuff ten-dons to the head of the humerus, any movement ofthe humerus must result in the rotator cuff tendonsthemselves “gliding” under the arch in the interfaceformed by the acromion, coracoacromial ligament,coracoid process, and conjoint tendons (Figure 4-19,A and B). Smooth movement of this “sphere” formedby the humeral head and cuff tendons preciselywithin the socket created by the subacromial arch is

dependent on many factors, the most important ofwhich are synchronized and coordinated contrac-tions of muscles moving the humerus and scapula,the laxity of the glenohumeral joint capsule, thesmoothness of the undersurface of the coracoacro-mial arch, and the smoothness and thickness of therotator cuff tendons.

As a result of the arrangement of rotator cuff ten-dons within this space, two surfaces of the rotator cufftendons are described: the bursal surface of the tendons,which refers to the superior aspect of the infraspina-tus–teres minor complex, supraspinatus, and sub-scapularis, and the articular surface of the cuff tendons,which refers to the deepest part of the cuff tendons.This deep part of the cuff tendons is that portionblending in with the superficial aspect of the gleno-humeral joint capsule.

This anatomical arrangement would suggest thatfriction might occur between the rotator cuff tendonsand the undersurface of the coracoacromial arch andresult in the bursal surface of the tendons, especially


Acromionprocess Coracoacromial

ligament

Coracoidprocess

Conjointtendon

Figure 4-17. The suprahumeral-subacromial interfaceis shown when the concave hood is formed (from poste-rior to anterior) by the acromion process, coracoacromialligament, coracoid process, and conjoint tendon of theshort head of the biceps and coracobrachialis. The con-vex humeral head moves within this concavity, which ispart bony tissue and part specialized connective tissue.

Glenohumeraljoint capsule

Supraspinatus

Bicepstendon(long head)

Subscapularis

Subacromial bursa

Infraspinatus

Teresminor

Figure 4-18. Interposed between the concave under-surface of the acromion and the convex humeral headare the rotator cuff tendons, subacromial bursa, bicepstendon (long head), joint capsule, coracohumeral liga-ment, and superior glenohumeral ligament.

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the infraspinatus and supraspinatus, showing the ear-liest signs of tendon degeneration. This does notappear to be the case. Instead, the earliest signs of cuffattrition occur on the articular side of the tendon, anobservation first noted by Codman in one of his clas-sic manuscripts on the shoulder (Figure 4-20).7,19,58

The most distal region of the rotator cuff tendons isthat portion attaching to the tuberosities of thehumerus. It typically shows the first signs of rents inthe tendons, cell disruption, loss of uniformity of thecollagen bundles, and a loosening of the fibers fromtheir attachment.45 The initial point of rotator cuff

degeneration is the anterior aspect of the supraspina-tus on its articular side, a region immediately adjacentto the long head of the biceps tendon. As cuff degen-eration advances, it begins to involve more of thesupraspinatus tendon and then typically extends intothe adjacent portion of the infraspinatus tendon(Figure 4-21).24,38

This short discussion of the degenerative processassociated with the rotator cuff is important to ourunderstanding of the effect that cuff degeneration mayhave on the integrity of the suprahumeral-subacromialinterface. The thickness of the cuff tendons serves as


A. FLEXION B. EXTENSION

Figure 4-19. Motion of thehumerus on the glenoid allows thesuperior aspect of the rotator cufftendons to glide under the concavehood formed by the acromion,acromion process, coracoacromialligament, and conjoint tendons.Note the position of the rotator cufftendons under the hood (A) whenthe humerus is flexed and (B) whenit is extended.

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the spacer that lies between the humeral head and theundersurface of the arch. This is relevant to shouldermechanics because the pull of the deltoid results in asuperior translational force of the humeral head on theglenoid (Figure 4-22). Thinning of the rotator cuff ten-dons can result in the humeral head riding superiorlybecause of deltoid contraction and more closelyapproximating the undersurface of the coracoacromialarch. In addition, the superior translation of thehumeral head has the potential to further erode thesuperior lip of the glenoid labrum and the complexinsertional region of the long head of the bicepstendon.

The rotator cuff plays the key role in minimizingthis translation of the humerus both actively and pas-sively when the deltoid contracts. Deficiency of thecomplete rotator cuff results in significant translationof the humeral head with deltoid activity.53 The supe-rior migration of the head of the humerus results inthe head no longer being centered within the glenoid,which in further compression of the cuff tendons andbursa, affects the undersurface of the coracoacromialligament and the biceps tendon. If, however, only thesupraspinatus is markedly degenerated, the patterns ofmotion of the humerus on the glenoid are not signifi-cantly altered because the subscapularis and the infra-spinatus are reasonably effective in maintaining thehead of the humerus in the glenoid.57

Two pathoanatomical changes to the arch haveclinical relevance. The first is the anatomical change

that occurs in the coracoacromial ligament. Note thatwhen the head of the humerus pushes up into theundersurface of the coracoacromial ligament, the lig-ament is forced to deform (see Figure 4-22). Suchdeformation of the ligament results in a traction forceat the ligament’s attachments, namely, the anterioraspect of the acromion process and the posterioraspect of the coracoid process. This continuous micro-trauma to the coracoacromial ligament can result inseveral structural changes. One is the thickening androughening of the undersurface of the ligament. Theother is a change in the shape of the acromion viaresultant traction spurs that develop in the region of theattachment of the ligament to the acromion.16,18,62

When you understand these mechanisms, it sheds adifferent light on the varying shapes of the acromion


Figure 4-20. The earliest signs of rotator cuff attritionoccur on the articular side of the tendon, rather than thebursal side.

Cuff degeneration

Figure 4-21. The anterior aspect of the supraspinatustendon near its insertion into the greater tuberosity is oneof the earliest locations of cuff degeneration. This regionis immediately adjacent to the long head of the bicepstendon. From this location the degenerative process canextend through the supraspinatus tendon and into theadjacent infraspinatus tendon.

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seen on radiographic evaluation (Figure 4-23). Whilesome of the different acromial shapes may be congen-ital, it appears reasonable that the shaping of theacromion process also might be an acquired phenom-enon, which occurs because of the continuous andprolonged loading patterns subjected to it, especiallythe force of the head of the humerus on the under-surface of the coracoacromial ligament. The threeacromial shapes most often described in clinical litera-ture are Type I, which is relatively flat, Type II, whichis curved in shape, and Type III, which resembles ahook.3

The second pathoanatomical change of note occursin the long head of the biceps tendon. Figure 4-24shows “flattening” of the long head of the biceps ten-don with a resultant vertical crease across its substancebecause of its being trapped and subsequently

Increased compression

Figure 4-22. The pull of the deltoid results in a forcethat translates the humeral head superiorly. The interpo-sitioning of the healthy, thick rotator cuff tendon acts asa spacer preventing movement of the head of thehumerus superiorly. Thus the head of the humerusremains centered within the glenoid. This compressionhas the potential to cause deformation or thickening ofthe coracoacromial ligament. The trauma to the under-surface of the ligament results in degeneration of theundersurface and traction spurs at the intersection of theligament with the acromion process.

Type I

Type II

Type III

Figure 4-23. The typical shapes of the acromion includeType I, a relatively flat acromion; Type II with a morecurved presentation; and Type III with a hook-shapedappearance. These different shapes may be acquiredbecause of the force of the humeral head against the under-surface of the acromion and coracoacromial ligament.

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compressed between the humeral head and the cora-coacromial arch.51,60 With severe attrition of the cufftendons, the cuff spacer effect is lost and the compres-sive trauma to the biceps tendon can result in loss ofbiceps tendon integrity with resultant rupture.

The subacromial interface is thus a socket in and ofitself under which the head of the attached rotatorcuff tendons must glide with any motion of thehumerus. Smooth motion within this socket is depend-ent on the congruence of the surface of the subacro-mial socket with the surface of the rotator cufftendons. Motions of the glenohumeral joint that bringthe greater tuberosity in close approximation to thecoracoacromial arch render the soft tissues vulnerable.These motions are noted in Table 4-3 and should beconsidered during evaluation of the shoulder.

The recognition of the intimate relationshipbetween the cuff tendons and the undersurface of thecoracoacromial arch has led to the development oftests used to assess for compromise of the tissueshoused in this space. Although often termed impinge-ment tests, it is clear that this region is much more com-plex and making a diagnosis by simply attempting tosqueeze the cuff tendons under the arch may notalways provide accurate answers. Despite limitations,impingement tests are an important part of the exam-ination process for the patient presenting with shoul-der pain because such tests begin to provide cluesabout the health of the tissues in this highly special-ized region.

Numerous tests have been described, but those initi-ated by Neer and Walsh along with the application ofthe examination techniques were among the first.42

The classic impingement test uses a maneuver in whichpassive full elevation of the arm with overpressure atendrange resulted in compression of the supraspinatustendon under the coracoacromial arch (Figure 4-25, A).The forced elevation was intended to reproduce thepatient’s pain. If, following injection of a local anes-thetic into the subacromial space, the pain was absentwith the same maneuver, a cuff impingement was sus-pected. The Hawkins test places the humerus that isflexed to 90 degrees in full internal rotation in order toattempt to directly compress the greater tuberosity(with the attached supraspinatus tendon) against theundersurface of the coracoacromial ligament (Figure4-25, B).27 Burns and Whipple noted that the cora-coacromial ligament is in contact with the supraspina-tus and biceps tendons as well with varying arcs ofshoulder motion (Figure 4-25, C).5 Such findings haveled to treatment of chronic cases of impingement viacoracoacromial ligament resection in order to decreasecompression to the underlying tendons.


CUFF DEGENERATION


Figure 4-24. As a result of the thinning of the rotatorcuff tendons caused by cuff tendon degeneration, thelong head of the biceps tendon becomes wedgedbetween the head of the humerus and the coracoacro-mial arch. This results in a crease in the biceps tendonand the possibility of biceps tendonitis or a completebiceps tendon tear associated with partial or full thick-ness tears of the rotator cuff tendons.

Table 4-3. Compromising theSubacromial Space: Bringing the

Greater Tuberosity Closer tothe Coracoacromial Arch

1. Excessive superior translation of humeral head2. Excessive anterior translation of humeral head3. Limited external rotation of humerus4. Decrease in scapular upward rotation5. Altered scapular kinematics during motion

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Figure 4-25. The classic impingement test is demonstrated when, A, the humerus is pushed into fullforward elevation and overpressure is given to determine if pain is reproduced; B, based on theHawkins test, the examiner brings the arm to 90 degrees and maximally to internally rotate thehumerus, seeking to reproduce the patient’s pain; or, C, as we prefer, the examiner places one hand overthe top of the acromion and clavicle to fixate the scapula in downward rotation while forcibly elevat-ing the humerus in varying arcs of motion and with varying degrees of internal and external rotation.

A B

C

New anatomical studies of the various impinge-ment tests have caused clinicans to reconsider theeffect such tests might have on the articular side of thecuff tendons, which is the initial site of tendon degen-eration.59 Although this has been discussed in

Chapter 3, it is worthwhile that you briefly revisit thisclinical entity in the context of shoulder articulations.In these cases the deep surface of the supraspinatustendon (articular side of the tendon) becomes com-pressed against the superior glenoid with all of the

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classic impingement positions. Whereas attrition ofthe bursal side of the cuff tendons is often consideredto be age related, young athletes in sports requiringoverhead activity, such as throwing sports, racquetsports, volleyball, swimming, and weightlifting, areoften confronted with articular side lesions of the rota-tor cuff tendons. Compression of the deep surface ofthe tendon against the glenoid rim is referred to asinternal impingement.13 Such impingements occurbetween the undersurface of the tendon and theposterior-superior rim of the glenoid fossa and are sec-ondary to repetitive microtrauma.56 With the arm inthe position of abduction, external rotation, andextension, there is markedly increased contactbetween the undersurface of the supraspinatus tendonand the posterior-superior border of the glenoid rim.The reader can appreciate that thousands of move-ment cycles in and out of this position result inincreased friction and compressional loading betweenthe tendon and rim.

Therefore the examiner must be cautious in the inter-pretation of pain with impingement tests since repro-duction of symptoms may be due to bursal sideinvolvement of the tendon, articular side involvement ofthe tendon, or both. It is important to move the humerusthrough various positions of potential cuff tendon stressin order to gain a better picture as to the positions andloads that reproduce the patient’s symptoms.

It is clear that the discussion of impingement prob-lems related to the suprahumeral-subacromial inter-face has markedly expanded beyond the simpleconcept of compression of the supraspinatus tendonunder the coracoacromial ligament. Our expandedunderstanding is not simply academic: treatmentinterventions are based on etiological factors associ-ated with the syndrome, and the cause of the impinge-ment phenomenon must be identified in order to treatit most effectively. Impingement causes can includethose ranging from hypomobility to hypermobility ofthe glenohumeral joint, loss of normal scapulotho-racic kinematics, and rotator cuff weakness andfatigue. Finally, the location of the lesion can rangefrom internal to external to full thickness.

THE ACROMIOCLAVICULARJOINT

We discuss the acromioclavicular joint at this pointin the text in order to review its mechanics andbecause the location of the inferior aspect of the joint

is in the coracoacromial arch and may be a contribut-ing factor in impingement syndromes. Changes instructure and function of the joint because of injuryor degeneration can result in a compromise to thesuprahumeral space.

The acromioclavicular joint is formed by the distalend of the clavicle and the medial aspect of theacromion. The clavicle is shaped like a “lazy S.”From its attachment to the acromion, it courses pos-terior and then anterior to terminate on the sternum,forming the sternoclavicular joint. The clavicleserves as a source of muscle attachment (see Chapter3) but also serves as the anterior “stabilizer” or“strut” for the scapula and glenohumeral joint. Theacromioclavicular joint is unusual in that the twoapproximating bony ends have a variety of subtle dif-ferences in shape and joint planes, and the articula-tion, formed by two flat surfaces approximating eachother, seems poorly designed to withstand the stressesthat reach the shoulder with activities of daily livingand sports.

The distal end of the clavicle typically rides higherthan the acromion, which makes the palpation of theacromioclavicular joint line relatively easy on mostpatients (Figure 4-26). Although the joint surfaces arelined with hyaline cartilage in children and teenagers,both surfaces have fibrous cartilage by a young adultage. The joint cavity of the acromioclavicular jointalso features a small meniscus or meniscoid inclusion.This meniscoid inclusion typically extends into thejoint from the superior aspect of the joint capsule.Little is understood about the roles of this oddlyplaced meniscus, but as seen with other menisci in thebody, it is assumed that the meniscus helps in the dis-tribution of synovial fluid and in attenuation of thedifferent forces that reach the joint. The disc degen-erates during adulthood, at which time it essentiallyfunctions poorly or not at all.48

Because the disc is so poorly developed and the sur-faces of the joint have such poor congruency, it is dif-ficult for the acromioclavicular joint to dissipate forcesin the manner seen in other joints. The weight-bearingsurface area is small, and therefore forces distributedover this small area result in very large pressure (P =F/A). Large compressive and shear loads can resultfrom simple activities in which the arm becomesweight bearing, such as leaning on our elbows or push-ing a heavy object away from our body. In addition,the large pectoralis major muscle exerts significantcompressive forces over the acromioclavicular joint byvirtue of its attachments. Because of this peculiar


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anatomy and associated influence on the mechanics,degenerative joint conditions of the acromioclavicularjoint are very common.15,28 Furthermore, a high inci-dence of coexisting pathological conditions withsymptomatic acromioclavicular joint problems, suchas biceps tendon pathology, full or partial thicknessrotator cuff tears, and tears of the glenoid labrum,have been demonstrated.4

Motion of the scapula on the clavicle at theacromioclavicular joint is not as great as often sug-gested. The joint surface is designed to permit asmall amount of sliding and rotational movementwhile transferring forces to the sternum through thelong axis of the clavicle. In 1934 Codman noted thatthere was minimal motion at the acromioclavicularjoint and stated that this joint “swings a little, rocks alittle, twists a little, slides a little, and acts as ahinge.”7 This simple statement is still a most accuratedescription of this joint. Very little motion occursseparately between the clavicle and acromion, andthat is the reason why the joint can be surgicallyfused without marked disruption of shoulder girdlemechanics. Instead, the motion of the scapula andclavicle typically occurs together and in synchronyinstead of independently.52 Approximately 20degrees of motion of the scapula on the clavicle

occurs in the frontal and sagittal planes, which isprobably more a function of the deformability of theligamentous framework supporting the joint than theactual osteokinematics. A variety of scapular posi-tions are thus possible, all to optimally set a scapularplatform from which the glenohumeral muscles canwork, including a clockwise or counterclockwise rota-tion of the scapula on the clavicle and a tilting of thescapula along a vertical axis, which allows the gle-noid to face anteriorly or more directly laterally(Figure 4-27, A and B).

The clinician needs to recognize the mechanics ofthe acromioclavicular joint when designing exercisesfor the upper extremity in the presence of acromio-clavicular joint arthritis. For example, a flat benchpress (Figure 4-28, A) has the potential to excessivelyload the acromioclavicular joint not only because ofthe compressive load occurring as a result of pectoralismajor contraction but also because of the forcedretraction of the scapula and endrange loading of theacromioclavicular joint in the chest position. Severalselectorized and plate-loaded resistance exercise unitsplace significant stress on the acromioclavicular joint(Figure 4-28, B and C ).

The clavicle also has the potential to rotate on itslongitudinal axis. This motion primarily occurs at the


Figure 4-26. Because the clavi-cle typically rides a bit higher thanthe acromion, the joint line of theacromioclavicular joint can beeasily palpated in most patients.

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sternoclavicular joint, however, and as a result ofscapulothoracic rotation (i.e., upward rotation of thescapula). This rotation is possible mostly because ofthe attachment of the coracoclavicular ligaments tothe lateral undersurface of the clavicle (Figure 4-29,A). When the scapula moves into upward rotation (asa result of contraction of the serratus anterior andupper and lower trapezius muscles), the coracoidprocess moves inferiorly. Because the coracoclavicularligaments run superiorly from the coracoid to attachto the clavicle, this movement of the scapula pulls theposterior aspect of the clavicle downward as a result ofthe downward movement of the coracoid process,

effectively causing a rotation of the clavicle on its lon-gitudinal axis (Figure 4-29, B).

The articulation between the clavicle andacromion is inherently unstable, and because thejoint has the above mentioned motion requirements,its stability is largely a result of the specialized con-nective tissue structures, namely the acromioclavicu-lar ligaments and the coracoclavicular ligaments.The stronger superior acromioclavicular joint liga-ment and weaker inferior acromioclavicular joint lig-aments surround the joint capsule. The superior andinferior acromioclavicular ligaments are not, how-ever, the primary sources of acromioclavicular joint


Figure 4-27. Two of the motions that occur at the acromioclavicular joint are, A, rotation of thescapula in a clockwise or counterclockwise direction, and B, motion of the scapula around a verti-cal axis, which allows the glenoid to have a more anterior or lateral presentation.

A B

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stability. The orientation of these ligaments is such thatthey help check anterior-posterior translational stress ofthe clavicle on the acromion, or acromion on the clavi-cle. The potential shifting of the clavicle posteriorly onthe scapula or the scapula posteriorly on the clavicle ischecked by the acromioclavicular joint ligaments.17

In contrast, the stability of the acromioclavicularjoint, especially in regard to superior-inferior move-ment of the clavicle on the acromion, or theacromion on the clavicle, is largely ensured by the twoportions of the coracoclavicular ligament, the conoidand trapezoid (see Figure 4-29, A). The two-part cora-coclavicular ligament is a short, stout ligament thatattaches along the apex of the convexity of the lateral

clavicle. Figure 4-30, A, shows the extent of theattachment of the coracoclavicular ligaments alongthe clavicle. The strong coracoclavicular ligament isthe primary restraint against the scapula moving infe-riorly on the thorax away from the clavicle. Thedirection of the fibers also suggests that the ligamentcounters or checks the strong pull of the trapezius,which is attached to the lateral clavicle. The readercan appreciate the strength of the coracoclavicularligament by considering that the scapula and attachedupper extremity literally “hang” from the clavicle viathe stout coracoclavicular ligament (Figure 4-30, B).Disruption of this ligament markedly diminishes thevertical stability of the scapula.


Figure 4-28. A, In the flat bench press, the acromioclavicular joint is often forced to its endrangeposition, which can be extremely problematic for an acromioclavicular joint with slight degenerativechanges. B, Use of the incline bench press places less stress on the acromioclavicular joint becausethe scapula is not brought into such extreme retraction. C, Note that the bilateral pec deck exerciseunit also has the potential to take the scapula into extreme endranges on the clavicle.

B

C

A

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Movement of the glenohumeral and scapulothoracicarticulations ultimately terminates at the sternum viathe clavicle. The acromioclavicular joint essentially actslike a stabilizing arm that has articulations at either endpermitting accommodation or translatory movement.This anatomical relationship is much like a tie rod in anautomobile, which functions to stabilize and directmovement from one surface to another.

Mechanical disorders of the acromioclavicular jointcan be due to several factors. A fall directly on theacromion process, especially with the arm adductedinto the body, violently pushes the scapula inferiorly,which potentially disrupts the acromioclavicular liga-ments, joint capsule, and coracoclavicular ligaments.Acromioclavicular joint sprains are typically classifiedas Type I through VI injuries with an increasing level ofbony, ligamentous, and muscle disruption that is more

pronounced in Types IV, V, and VI (Table 4-4). Thefirst three classifications (Types I, II, and III) are themost common types seen in the ambulatory outpatientsetting. Type I injuries feature sprain of the acromio-clavicular ligaments, but since the coracoclavicular liga-ment is intact, there is no loss of joint stability. Type IIinjuries feature torn acromioclavicular ligaments butonly a sprain of the coracoclavicular ligament, andtherefore some joint stability is compromised. Type IIIinjuries feature a dislocation of the clavicular andacromion joint surfaces. Type III injuries are morecomplex than initially meets the eye because the attach-ments of the deltoid and the trapezius are also dis-rupted depending on the direction of the dislocation.The deltoid attachment on the lateral aspect of theclavicle and the acromion is in the same insertionalregion as the trapezius, and since both of these muscles


Conoidligament

Trapezoidligament

Upwardrotation

Figure 4-29. A, The coracoclavicular ligaments are composed of two components: the conoid lig-ament and trapezoid ligament extend from the superior aspect of the coracoid to the inferior aspectof the clavicle. B, As the scapula is upwardly rotated, the clavicle moves up and away from the cora-coid process. The coracoclavicular ligaments hold the posterior part of the clavicle downward, cre-ating rotation of the clavicle on its longitudinal axis.

BA

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span the acromioclavicular joint, they become compro-mised after Type III injuries and are more grossly dis-rupted by an injury classified as Type IV through VI.

The acromioclavicular joint can also be symptomaticas a result of degenerative joint disease, osteoporosis, orosteolysis of the lateral aspect of the clavicle. Osteolysisis seen primarily in individuals with repeated heavystresses to the shoulder, such as weightlifters or heavylaborers. Pain from the acromioclavicular joints is typi-cally felt along the C3-C4 dermatomal distribution,which is localized to the superior and anterior aspects ofthe shoulder. Referred pain may also be felt in theanterolateral neck and trapezius-supraspinatus region.20

It is not typical for pain from the acromioclavicular joint

to refer into the forearm or hand, and if such symptomsare present, the clinician should examine the completeupper quarter. Pain is often reproduced with palpation,and the joint can be provoked in the physical examina-tion by maximally horizontally adducting the arm thathas been elevated forward (Figure 4-31).

THE SCAPULOTHORACICINTERFACE

Nearly all shoulder function requires movement ofthe scapula concurrent with movement of the humerus.Scapular motion complements glenohumeral motion,


Trapezoid ligament

Conoidligament

Coracoid

Clavicle

Figure 4-30. A, This view shows the extent of the attachment of the coracoclavicular ligament(conoid and trapezoid components) along the inferior aspect of the clavicle. B, Appreciate thestrength of the coracoclavicular ligament. The scapula and upper extremity “hang” from the clavi-cle via the coracoclavicular ligament.

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and it also is essential to achieving the full range ofshoulder movement possibilities. For example, reachingcompletely forward is the summation of scapular pro-traction and shoulder flexion. Likewise, reachingbehind our back or attempting to scratch our own backrequires the humerus to be adducted, hyperextended,and internally rotated, and the scapula must beretracted and downwardly rotated as well. Thesemotions are complex because they involve movement ofthe scapula over the thorax, the scapula on the clavicle,and the clavicle on the sternum. While historically a 2:1ratio of glenohumeral motion to scapulothoracicmotion has been discussed, the scapular contribution to

elevation of the arm is much more complex in terms ofthe subtleties of the motion and highly variabledepending on the loads the arm is lifting.41

Because the scapulothoracic interface is limited tothe acromioclavicular joint and the glenohumeraljoint in terms of bony articulations, and the scapula isonly indirectly attached to the axial skeleton at thesternoclavicular joint via its linkage to the clavicle, thescapula is almost entirely dependent on the muscula-ture for its mobility, as well as its ability to be fixatedor stabilized on the thorax. The Kibler lateral scapu-lar slide test is designed to look at the posture of thescapula as it rests on the thorax.14,32,33 In this test the

Table 4-4. Acromioclavicular Joint Injuries

Pathology Clinical Findings Management

Type I

Minor sprain of AC ligaments Tender to palpation Ice, sling 5-7 daysIsometrics, ROMReturn to activity after 2 weeks

Type II

AC ligament rupture Pain with provocation Ice; sling 1-3 weeksDistal clavicle unstable Higher riding clavicle Isometrics, ROM when symptoms

decreasedCoracoclavicular ligaments intact Accessory motion increased Return to activity after 2-4 weeks

May have residual deformity

Type III

AC ligament rupture Marked deformity, asymmetry Ice; sling 2-4 weeksCoracoclavicular ligament rupture Distal end of clavicle unstable and Isometrics, ROM when tolerated

palpableDeltoid, trapezius disruption Consider surgical repair

Type IV

AC ligament rupture Marked deformity and disability SurgeryCoracoclavicular ligament ruptureDeltoid, trapezius disruptionClavicle lodged in trapezius

Type V

AC ligament rupture Marked deformity and disability SurgeryCoracoclavicular ligament ruptureDeltoid, trapezius detachmentMarked displacement of clavicle

Type VI

AC ligament rupture Marked deformity and disability SurgeryCoracoclavicular ligament ruptureDeltoid, trapezius disruptionClavicle displaced behind coracoid

process and conjoint tendonsRib and soft tissue injury

ROM, Range of motion; AC, acromioclavicular joint.

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Figure 4-31. In a provocationaltest of the acromioclavicular joint,the arm is flexed and brought intohorizontal adduction and thengentle overpressure is applied.

distance from the inferior angle of the scapula to thecorresponding thoracic vertebra is measured for bothscapulae. Then both sides are compared after plac-ing the arms in three different positions: at the side,with the hands on the hips, and at 90 degrees abduc-tion with full glenohumeral internal rotation.Differences of less than 1 cm bilaterally are consid-ered normal, whereas differences greater than 1.5cm are considered abnormal. Litchfield and co-workers noted further that the Kibler lateral slide testwas valid for helping to identify patients withimpingement.36 In other words, patients with sus-pected scapular asymmetry had evidence ofimpingement syndrome.

Although the term scapulothoracic interface is used toimply motion of the scapula on the thorax, the motioninterfaces are actually between the deep aspect of theserratus anterior muscle and the ribs, intercostal mus-cles, and serratus posterior muscles and between thedeep surface of the subscapularis muscle and the super-ficial surface of the serratus anterior muscle. Severalbursae are present at these interfaces. One large bursais located at the superior medial corner of the scapulaand lies between the serratus anterior and subscapularismuscles. Another large bursa that typically is prominentin most shoulder dissections lies between the serratusanterior muscle and the lateral wall of the chest.Therefore the scapula lies within a canopy of muscles,

and it is the muscles that must move freely among oneanother, as well as across the thoracic cage.

While “snapping scapula” is often thought to be acondition related to the movement across thickenedbursal tissue, the causes of this syndrome areunknown. It may be caused by a variety of reasonsincluding bony exostosis of the undersurface of thescapula or the ribs, neoplasms of the scapula, or exces-sive weight loss or muscle atrophy, in which the mass ofthe subscapularis or serratus anterior no longer pro-vides a thick cushion in which the scapula can sit.

In addition, a change in the position of the thoraxitself alters the position of the scapula at this scapu-lothoracic interface. For example, the forward head,rounded shoulder posture seen so often in the clinicalexamination is often due to a thorax that is now cau-dal and forward as a result of abdominal wall weak-ness. This collapse of the thorax forward results in thescalene muscles and sternocleidomastoid muscles pas-sively pulling the cervical spine forward and also posi-tions the scapula in protraction and downwardrotation, which potentially compromises the tissueswithin the subacromial space. The relationship of theabdominal wall to the shoulder girdle muscles is detailedin Chapter 3.

Motion of the scapula occurs in numerous direc-tions and planes simultaneously. Motions includeupward and downward rotation of the scapula

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(glenoid facing upward or downward, respectively),protraction and retraction (also referred to as abductionand adduction, respectively), elevation and depression,tilting about a frontal axis, and tilting about a verticalaxis (Figure 4-32, A-E ). The wide range of scapularmovement is designed to provide optimal positioningof this important bone so that the muscles originatingfrom it and moving the humerus are functioning attheir optimal length-tension relationship. Scapularmotion and muscle strength and endurance of themuscles directly moving the scapula are essential com-ponents of shoulder function. McQuade and col-leagues noted that fatigue of the shoulder muscles hasa pronounced effect on the synchrony of movementbetween the scapula and the humerus with a con-comitant change in expected scapulohumeralrhythm.40 This has significant implications for loaddistribution at the glenohumeral joint and at the

suprahumeral region for sport activities and repetitivemotions associated with the work setting.

Treatment of many acute neck disorders is oftenbest begun with passive mobilization techniques of theshoulder.50 Because scapulothoracic motion is soessential for functional shoulder motion, mobilizationof the scapula is extremely important in the treatmentof many shoulder conditions, including frozen shoul-der, or adhesive capsulitis syndromes, postsurgicalrehabilitation for rotator cuff repair, repair ofhumeral fractures, and capsular repairs. Such mobi-lization techniques are safe and help modulate painand maintain and restore motion of this key interface(Figure 4-33).

Several muscles move the scapula directly by virtueof their attachments. These include the serratus ante-rior, trapezius, rhomboid major and minor, pectoralisminor, and levator scapulae (see Chapter 3). Several

Figure 4-32. It is important to understand the various motions of the scapula relative to the tho-rax: A, upward and downward rotation; B, protraction and retraction; C, elevation and depression;D, tilting about a frontal axis; and E, tilting about a vertical axis.

B

C D E

A

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other key muscles move the scapula indirectly byvirtue of their attachments to the humerus. Theseinclude the latissimus dorsi (scapular depression andretraction) and pectoralis major (scapular depressionand protraction). Finally, it is important to realize thesynergistic activity of the thoracoscapular and scapu-lohumeral motions with everyday activities (Figure 4-34). For example, when you pull a heavy weighttoward your body, which requires strong activity ofthe humeral extensor, such as the posterior deltoidand the teres major, the scapula must be fixated sothat these muscles have a stable origin to pull from. Inthis example, the scapula retractors, such as therhomboids and middle trapezius, must strongly fixatethe scapula in order to allow the posterior deltoid andthe teres major to effectively move the humerus.

THE STERNOCLAVICULAR JOINT

The sternoclavicular joint is the upper extremity’sonly articulation with the axial skeleton, and thus theweight of the upper extremity is continuously trans-ferred through the clavicle to this important articula-tion. Disorders of the sternoclavicular joint (sprains of

the joint or dislocations) are relatively rare, whichimplies that the articulating elements, the medial endof the clavicle and the sternum, are highly congruousand result in bony stability. This is far from the case,however, as the bony elements result, when consideredalone, in the sternoclavicular joint being one of theleast stable joints in the body.

Like the glenohumeral joint, the sternum and clav-icle are poorly matched. Typically, less than half ofthe medial end of the clavicle is in contact with theconcave clavicular notch of the sternum. A close lookat the medial end of the clavicle reveals it to be sad-dle shaped, with its convex rim running vertically andits concave region running anterior to posterior(Figure 4-35, A). Given such poor congruency of thejoint partners, the stability of the joint must comefrom the ligaments, namely the anterior and posteriorsternoclavicular ligaments, interclavicular ligament,and the costoclavicular ligament, in addition to thearticular disc that supports the sternoclavicular joint(Figure 4-35, B).

The articular disc of the sternoclavicular joint isunique because it attaches inferiorly at the junctionof the first rib and sternum and then proceeds supe-riorly to attach to the superior aspect of the clavicle


Figure 4-33. Mobilization of thescapulothoracic interface is accom-plished from the side-lying position.The scapula can be easily grasped bythe examiner and passively movedacross the thorax for superior andinferior glides, protraction andretraction, or tilting of the scapulaalong a vertical axis. (From Porter-field JA, DeRosa C: Mechanical neckpain: perspectives in functional anatomy,Philadelphia, 1995, WB Saunders.)

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(Figure 4-35, C). Note how the articular disc preventssuperior and medial displacement of the clavicle onthe sternum. Superficial to the disc is the broad cos-toclavicular ligament (Figure 4-35, D). This ligamentis actually made of two parts and helps stabilize theclavicle.

Perhaps the key ligament that resists upward dis-placement of the clavicle away from the sternum isthe capsular ligament, particularly its anterior cap-sule component. Just like most capsular ligaments,the anterior and posterior sternoclavicular capsularligaments are thickenings of the joint capsule, withthe anterior in this case being quite substantial.Bearn’s classic work on sternoclavicular stabilitydemonstrates that the capsular ligaments strongly

resist the upward motion of the clavicle. The motionwould occur simply because of the weight of theupper extremity.2 The resting shoulder posture (pointof the shoulder being held up) is in large part a resultof the ligamentous structure of the sternoclavicularjoint resisting upward displacement of the clavicle’ssternal end (Figure 4-36, A).

The motion of the scapula over the scapulothoracicinterface results largely from the mobility present atthe sternoclavicular joint (Figure 4-36, B). Motionoccurs in the horizontal and frontal planes, and rota-tion occurs around the longitudinal axis of the clavi-cle. This capability at the sternoclavicular joint plays agreat role in allowing the shoulder girdle its extraordi-nary mobility.


Rhomboids

Trapezius

Serratusanterior

Figure 4-34. The scapula must bestabilized by the serratus anterior,trapezius, rhomboids, and levatorscapulae when the glenohumeraljoint flexes past 90 degrees. If thescapula is not stabilized, the scapuladrops toward downward rotation,resulting in a decrease in thesuprahumeral space.

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Sternoclavicularjoints

ClavicleArticular disc

Sternum

First rib




Figure 4-35. A, The medial end of the clavicle is saddle shaped, with its convex rim running ver-tically and its concave region running anterior to posterior. B, This large medial prominence (ster-nal end of the clavicle) is poorly matched to the clavicular notch of the sternum, as the notch is muchsmaller than the sternal end of the clavicle. C, The articular disc of the sternoclavicular joint passessuperiorly from the junction of the ribs and the sternum to the superior surface of the clavicle, effec-tively dividing the joint into two compartments. D, The costoclavicular ligament originates from thejunction of the first rib and the sternum and courses superiorly to attach to the inferior margin ofthe sternal end of the clavicle. The broadness of this ligament results in it stabilizing rotary and ele-vation movements of the clavicle on the sternum.

B

C

D

A

SUMMARY

We reviewed the articulations of the shoulder gir-dle in this chapter, including the synovial joints andkey interfaces allowing shoulder motion. The studyof each articulation of the shoulder girdle under-scores the synchrony necessary among all movingparts and implies that dysfunction in one of the

articulations or interfaces can result in overload orrepetitive strain in another region. Therefore it isessential that the clinician evaluate each articulationof the shoulder girdle in order to make the most accu-rate diagnosis and direct a course of treatment aimedat addressing the cause of the problem instead of sim-ply treating the symptoms associated with the disor-der. The application of the clinical anatomy of any

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region of the body is best illustrated in the evaluationprocess for that region. In Chapter 5 we present theevaluation of the shoulder in the context of itsanatomical region.

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Figure 4-36. The sternoclavicular capsular ligaments and the articular disc of the joint stronglyresist upward motion of the clavicle on the sternum. Note how this contributes to resting shoulderposture (A). The weight of the upper extremity pulls down on the lateral aspect of the claviclethrough the scapula, as seen in B, and the medial end of the clavicle would rise from the sternal basewithout this ligamentous checkrein.

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23. Guidi EC, Zuckerman JD: Glenoid labral lesions. In Wilk KE,Andrews JR, editors: The athlete’s shoulder, New York, 1994,Churchill Livingstone.

24. Hadler A, Zobitz ME, Schultz F, et al: Mechanical properties ofthe posterior rotator cuff, Clin Biomech 15:456, 2000.

25. Hannafin JA, DiCarlo ED, Wickiewicz TL, et al: Adhesive cap-sulitis: capsular fibroplasias of the glenohumeral joint,J Shoulder Elbow Surg 3S:5, 1994.

26. Harryman DT II, Sidles JA, Matsen FA III: Laxity of the nor-mal glenohumeral joint: a quantitative in vivo assessment,J Shoulder Elbow Surg 1:66, 1992.

27. Hawkins RJ, Kennedy JC: Impingement syndrome in athletes,Am J Sports Med 8:151, 1980.

28. Henry MH, Liu SH, Loffredo AJ: Arthroscopic management ofthe acromioclavicular disorder: a review, Clin Orthop 316:276,1995.

29. Howell SM, Galinat BJ: The glenoid-labral socket: a con-strained articular surface, Clin Orthop 243:122, 1989.

30. Howell SM, Galinat BJ, Renzi AG, et al: Normal and abnormalmechanics of the glenohumeral joint in the horizontal plane,J Bone Joint Surg Am 70A:227, 1988.

31. Kelkar R, Flatow EL, Bigliani LU, et al: A stereophotogram-metric method to determine the kinematics of the gleno-humeral joint, Adv Bioeng 19:143, 1992.

32. Kibler WB: Role of the scapula in the overhand throwingmotion, Contemp Orthop 22:525, 1991.

33. Kibler WB, Livingston BR: Current concepts in shoulder reha-bilitation, Adv Oper Orthop 3:249, 1995.

34. Kronberg M, Brostrom LA, Soderlund V: Retroversion of thehumeral head in the normal shoulder and its relationship tothe normal range of motion, Clin Orthop 253:113, 1990.

35. Lippitt SB, Vanderhooft JE, Harris SL, et al: Glenohumeralstability from concavity-compression: a quantitative analysis,J Shoulder Elbow Surg 2:27, 1993.

36. Litchfield R, Hawkins R, Dillman CJ, et al: Rehabilitation ofthe overhead athlete, J Orthop Sports Phys Ther 18:433, 1993.

37. Ludewig PM, Cook TM: Alterations in shoulder kinematicsand associated muscle activity in people with symptoms ofshoulder impingement, Phys Ther 80:276, 2000.

38. Matsen FA III, Lippitt SB, Sidles JA, et al: Practical evaluation andmanagement of the shoulder, Philadelphia, 1994, WB Saunders.

39. McMahon P, Debski R, Thomson W, et al: Shoulder muscleforces and tendon excursions during glenohumeral abduc-tion in the scapular plane, J Shoulder Elbow Surg 4:199,1995.

40. McQuade KJ, Dawson J, Smidt GL: Scapulothoracic musclefatigue associated with alterations in scapulohumeral rhythmkinematics during maximum resistive shoulder elevation,J Orthop Sports Phys Ther 28:74, 1998.

41. McQuade KJ, Smidt GL: Dynamic scapulohumeral rhythm:the effects of external resistance during elevation of thearm in the scapular plane, J Orthop Sports Phys Ther 27:125,1998.

42. Neer CS, Welsh RP: The shoulder in sports, Orthop Clin NorthAm 8:583, 1977.

43. Neviaser JS: Adhesive capsulitis of the shoulder, J Bone Joint Surg27:211, 1945.

44. Neviaser JS: Adhesive capsulitis and the stiff and painful shoul-der, Orthop Clin North Am 11:327, 1980.

45. Nixon JE, DiStefano V: Ruptures of the rotator cuff, Orthop ClinNorth Am 6:423, 1975.

46. Norris TR, Fischer J, Bigliani LU: The unfused acromial epi-physis and its relationship to impingement syndrome, OrthopTrans 7:505, 1983.

47. O’Brien SJ, Neves MC, Arnocsky SP, et al: The anatomy andhistology of the inferior glenohumeral ligament complex ofthe shoulder, Am J Sports Med 18:449, 1990.

48. Petersson CJ: Degeneration of the acromioclavicular joint: amorphological study, Acta Orthop Scand 54:434, 1983.

49. Poppen NK, Walker PS: Normal and abnormal motion of theshoulder, J Bone Joint Surg (Am) 58:195, 1976.


51. Refior HJ, Sowa D: Long tendon of the biceps brachii: sites ofpredilection for degenerative lesions, J Shoulder Elbow Surg4:436, 1995.

52. Rockwood CA Jr: Dislocations about the shoulder. InRockwood CA Jr., Green DP, editors: Fractures, vol I,Philadelphia, 1975, JB Lippincott.

53. Sharkey NA, Marder RA, Hanson PB: The entire rotator cuffcontributes to elevation of the arm, J Orthopaedic Res 12:699,1994.

54. Snyder SJ, Banas MP, Karzel RP: An analysis of 140 injuries tothe superior glenoid labrum, J Shoulder Elbow Surg 4:243,1995.

55. Snyder SJ, Larzel RP, Del Pizzo W, et al: SLAP lesions of theshoulder, Arthroscopy 6:274, 1990.

56. Sonnery-Cottet B, Edwards TB, Noel E, et al: Results ofarthroscopic treatment of posterosuperior glenoid impinge-ment in tennis players, Am J Sports Med 30:227, 2002.

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59. Valadie AL, Jobe CM, Pink MM, et al: Anatomy of provocativetests for impingement syndrome of the shoulder, J ShoulderElbow Surg 9:36, 2000.

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GENERAL CONCEPTS

Pathomechanical VersusPathoanatomical Diagnosis

There are many tissues within the shoulder girdlecomplex that are potential sources of pain. In addi-tion, the cervical spine, visceral structures such as car-diac and pulmonary tissues, and select abdominalviscera, all have the capacity to refer pain to the shoul-der region. Once referred pain from visceral structureshas been ruled out, the clinician must identify the pre-cise anatomical tissue causing the painful syndromewithin the shoulder complex or determine thosemovements and combinations of applied stresses thatreproduce familiar signs or symptoms. The shouldercomplex can be assessed from either a pathoanatomi-cal or pathomechanical perspective. This may, how-ever, present a dilemma in the development of anactive treatment program or an exercise prescription.For example, does the clinician prescribe exercise inorder to minimize stress to a suspected lesion of thelong head of the biceps because he surmises that is thepainful tissue? Or does he prescribe exercises aroundthe nociceptive mechanics evaluated, designing anexercise program around the motions and forces thatclearly reproduce the patient’s signs and symptoms?The pathoanatomical approach to examination seeksto discover the tissue that might be at fault, whereasthe pathomechanical approach seeks to identify those

motions, postural positions, stresses, or combinationsof stresses that are contributing to the painful syn-drome.

The first and most basic question to ask is: What isthe precise anatomical lesion causing pain in mostshoulder conditions? Even a well-understood conditionsuch as impingement syndrome presents great diffi-culty in identifying the exact tissue that might be atfault. The anatomy described in Chapters 3 and 4 illus-trates that in addition to mechanical linkages andanatomical connections among the various tissues, thestructures lie in very close proximity to each other. Is itpossible, for example, to definitively conclude that painresulting from an impingement test is actually from theanterior aspect of the supraspinatus tendon rather thanthe posterior portion of the long head of the biceps ten-don, since they are so closely placed? Likewise, with theintimate blending of the anterior aspect of the infra-spinatus tendon to the posterior aspect of thesupraspinatus tendon, is it possible to identify the spe-cific symptomatic tendon? Shoulder instability providesanother example. Classic shoulder instability is rela-tively easy to identify based on information gained fromthe patient history and several passive motion maneu-vers. It is not as easy to identify the exact anatomicaltissue that is the nociceptive generator because somany tissues are typically compromised when theglenohumeral joint is unstable. Chapter 4 reviewed thepossible joint structures that might be implicated withinstability, along with the potential for secondary

CHAPTER 5FUNCTIONALASSESSMENT OF THESHOULDER GIRDLECOMPLEX

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compromise to surrounding tissues such as the rotatorcuff tendons and long head of the biceps.

Certainly the increased use of imaging and arthro-scopic techniques optimizes the chances of identifyingthe tissues that appear to have been injured or are inthe varying stages of degeneration. In some clinicalconditions the tissue at fault can in fact be identified.For example, the history of an abrupt loss of the abil-ity to lift the arm following shoulder trauma, coupledwith a positive drop-arm test (described later in detail)and diagnostic arthroscopy revealing a full thicknesstear of the supraspinatus tendon, allows us to appro-priately conclude which tissue is at fault.

In many shoulder syndromes the history, signs, andsymptoms are less clear. It is important to recognize thatthe similarities and differences between normal age-related changes and pathology have not been clearlyelucidated. It is difficult to be certain that the nocicep-tive generator in someone complaining of shoulderpain is due to pathology of the cuff tendons rather thansurrounding tissues because rotator cuff tendons beginto show age-related changes as early as the second andthird decades and yet can be asymptomatic.

Another example relates to glenoid labrum damage.We previously mentioned that the superior aspect ofthe glenoid labrum is less firmly attached to the gle-noid rim than the inferior aspect (see Chapter 4).Short of an obvious tear in the superior aspect of thelabrum, when should the superior labrum be consid-ered pathological because it is identified as “too loose”and hence diagnosed as a SLAP lesion (see Chapter 4)as opposed to simply being the normal loose attach-ment for that particular patient? Consideration of thequestions these clinical examples raise is fundamen-tally important because ultimately the conclusions thatthe examiner reaches after taking the history and con-ducting the physical examination direct the course oftreatment, whether it is surgical or nonsurgical.

The Concept of Applied Physical Stresses

Perhaps the most compelling reason for the thor-ough discussion of the shoulder anatomy in the pre-vious chapters is that it provides the clinician withan appreciation of the anatomy in three dimensions.Combining a comprehensive understanding of theanatomy and biomechanics of the articulationscomprising the shoulder complex with knowledgeabout fiber direction, connective tissue linkages,

and spatial relationships of the muscles allows theexaminer to resolve every force the patient appliesduring the physical examination into componentvectors. For example, what might look like a simpleanterior-to-posterior shear of the head of the hu-merus on the glenoid by the examiner with thepatient in the supine position may in fact havethe following concurrent stresses applied to associ-ated tissues:

1. Compression of all soft tissue (skin, anterior del-toid, vasculature, neural tissue, subscapularis, longhead of biceps tendon, joint capsule, coraco-humeral ligament, glenohumeral ligaments)between the skin and the head of the humerus

2. Compression of the head of the humerus into theposterior part of the labrum and glenoid if theapplication of the anterior-posterior shear stress isnot applied parallel to the glenoid surface

3. Stretch of the posterior joint capsule and the cuffmuscles reinforcing the posterior aspect of the cap-sule by movement of the humeral head against theinner capsule wall

We suggest that in the nonsurgical managementof many musculoskeletal conditions, it is not as crit-ical to determine the anatomical tissue that is at faultbut rather to find out what abnormal or excessivestresses or combinations of stresses are reproducingfamiliar pain by stimulating the nociceptive system.Nociceptive stimulation occurs as a result of the tis-sue’s inability to attenuate such stresses, typicallybecause of injury as a result of age-related tissuechanges.

Therefore the examination methods discussed inthis chapter largely describe efforts to reproducefamiliar symptoms through the application of threeprimary stresses: compression, tension, and shear.Whether the examination procedure involves activemotion, passive motion, resisted motion, palpation, orthe use of shoulder-specific special tests, the unifyingfeature of these tests is that they are typically assessingthe shoulder tissues’ ability to attenuate compression,tension, or shear. Such an approach provides clinicalutility for several reasons:30

● It allows the clinician to use the results of the exam-ination as the basis for designing an exercise pro-gram around these nociceptive mechanics.

● It correlates the patient’s vulnerable and invulnera-ble positions and movements to his work and activ-ities of daily living.

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● It provides information to the patients in under-standable and practical terms.

Thinking in terms of applied physical stresses alsoprovides meaningful information regarding the irri-tability of the tissues. The examiner needs to be ableto correlate the magnitude of their applied stress tothe ease or difficulty in evoking a painful response.The goal is to identify the intensity and direction ofthe forces used in the physical examination in orderto determine the relationship of the applied stressesto the painful syndrome. After this information hasbeen gained, an appropriate active treatment plancan be established, which minimizes further tissuedamage and promotes connective tissue and musclegrowth while simultaneously decreasing sensitivityto pain.

INFORMATION GAINED FROMTHE EXAMINATION

Perhaps no area of the musculoskeletal systembesides the shoulder complex has such a broad arrayof special tests available to help with assessment.Numerous tests have been described for the bicepstendon, thoracic outlet syndrome, and shoulder insta-bility, to name just a few. Indeed, there are enoughspecial tests for specific tissues of the shoulder to war-rant their own complete chapters in textbooks.

This presents a challenge for the examiner. Howcan a comprehensive clinical examination of theshoulder be conducted while maintaining a balancebetween thoroughness and efficiency? What are thebest tests to use? It is not enough to have a particularsequence of examination in mind. The clinician mustalso use the patient history in a manner that dictatesthe essential pieces necessary to the physical examina-tion so that he can conduct it in a manner that avoidsunnecessary redundancy while simultaneously sub-stantiating what has already been discovered up tothat point in the examination process.

Regardless of the examination scheme chosen,there are a few essential pieces of information thatmust be gleaned on completion of the history andphysical examination. Recognizing such end pointsallows the examiner to conduct an effective and effi-cient examination. The minimal essential pieces arethreefold and fall under the categories of pathomechan-ics, syndrome classification, and presence or absence ofstability.

Pathomechanics

During the physical examination the clinicianguides the patient through a series of systematicmotions and then applies various stresses and combi-nations of stresses to and through the tissues. Asimplied in the previous section, the examiner ulti-mately concludes which series of motions and combi-nations of stresses reproduce familiar pain. Theapplication of overpressure to these motions results inincreased tension, compression, or shear to the struc-tures. The clinician seeks the specific combination ofstresses that exacerbates the condition or provokes famil-iar pain. The pathomechanics that reproduce familiarpain or are recognized to yield atypical responses such asabnormal motion, muscle or motion guarding, orapprehension are acknowledged by the examiner andthen substantiated by applying similar stresses in otherpositions. Applying similar stresses with the shoulderin dependent and nondependent positions, for exam-ple, and from different starting points in the range ofmotion, allows the examiner to correlate theseresponses and determine their relationship to thepainful syndrome.

Syndrome Classification

The second piece of necessary information relatesto the syndrome presentation itself. Is the patient pre-senting with an acute shoulder problem, an exacerba-tion of a previous problem, or a syndrome exhibitingchronic pain behaviors? The great majority of shoul-der joint disorders fall into one of the first two cate-gories. It is only when there is evidence of little or nodirect relationship between the physical stimulusapplied in the examination and the pain responsefrom the patient, combined with the complaint of per-sistent pain well beyond expected healing time, thatthe clinician begins to consider the presence of chronicpain syndrome.

Acute injuries are those in which the response of thepatient to various stresses is proportional to the timesince the onset of the painful syndrome and thepathomechanics of injury. Because of the predictabil-ity of the healing times for many of the specializedconnective tissues and based on work that has beendone with spinal disorders, acute injuries are generallyconsidered to be those that are less than 7 weeks old.

Because acute injuries are typically accompanied byswelling and the associated alteration of the chemical

FUNCTIONAL ASSESSMENT OF THE SHOULDER GIRDLE COMPLEX 131

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milieu of the tissues, morning stiffness and discomfortare positive indicators of swelling and the acuteness ofthe injury. When an injured tissue is placed at rest andvery little movement occurs, fluid stasis chemicallyactivates the nociceptive system (see Chapter 6). Theremaining category of syndrome classification is theexacerbation of previous injury patient presentation.Within this group patients typically describe previousinjuries, past symptoms, or an antecedent event fromwhich a pattern of pain develops over the course oftime, with varying levels of pain intensity and varyingintervals of time between episodes. The pain patterndescribed gives the examiner a sense of the limitedcapacity of the injured tissues to attenuate compres-sion, tensile, and shear loads. This syndrome is relatedto tissues that have been previously subjected tomacrotrauma and those tissues affected by the age-related, degenerative processes. In both cases the opti-mal loading capacity or limit of the tissue’s toleranceto compression, tension, or shear is being exceeded(see Chapter 1). Patients in this category describe sim-ilar episodes of their unique problem, which typicallyworsen over time.

Presence or Absence of Stability

The third piece of information that must be deter-mined from the examination concerns the stability ofthe key articulations of the shoulder complex. Stabilityof the articulations within the musculoskeletal systemis primarily due to two reasons: the integrity of theconnective tissues associated with the articulations andthe status of the neuromuscular control over thesearticulations.16 This is especially true for the gleno-humeral joint. As seen in many other areas of themusculoskeletal system, the body type, connective tis-sue integrity, and neuromuscular health of the regiondetermine how the forces of weight bearing andmovement converge on the region and are attenuated.Do these forces result in aberrational motion betweenthe articulating structures, and is this abnormalmotion excessively loading support tissues and result-ing in stimulation of the nociceptive receptors associ-ated with the articulations? This is a key question thatthe examiner needs to ask while administering testsduring the examination process.

In Chapter 1 the concept of the optimal loadingzone of tissues was explained. In Chapter 3 the role ofthe muscular system over the articulations was dis-cussed in detail. Chapter 4 focused on the specialized

connective tissues associated with the shoulder. Theimportant point to be gleaned from these chapters isthat the precision and interplay of neuromusculocon-nective tissues are vital for joint stability and subtlechanges in any of these tissues have the potential tocontribute to joint instability. Therefore the patienthistory and physical examination for mechanical dis-orders of the shoulder have to be designed to ulti-mately confirm the presence or absence of stability,which then guides the examiner in determining thecausative factors if instability is suspected.

In the remaining sections of this chapter, we willprovide the reader with a pattern of examination foractivity related disorders of the shoulder complex.Using a consistent pattern of examination is impor-tant because it helps ensure thoroughness and allowsphysical findings to be compared among patients. Theexaminer must understand the potential relevance ofkey elements in the history and be able to administerimportant provocative tests to tissues, palpate keystructures, and identify those factors that may be con-tributing to the pain pattern or dysfunction at theshoulder. The composite of this information providesthe examiner with information regarding the patho-mechanics, the syndrome classification, and the pres-ence or absence of stability.

COMPONENTS OF THE PATIENTHISTORY

Initial Considerations

The patient history often dictates the direction thatthe remaining portion of the musculoskeletal exami-nation will take. During questioning, pay close atten-tion to patient affect, posturing, and willingness to giveinformation. Be a focused listener, and think in termsof joints or soft tissues under the area of complaintthat might be causing the problem and any anatomi-cal region that might refer pain to the shoulder andassociated regions of the upper quarter. Frame ques-tions in such a way that you and the patient can reacha common understanding of the problem. This is thefirst step in helping the patient recognize how impor-tant his role will be in the management of his prob-lem. During the history, the therapeutic relationshipbetween clinician and patient begins, as well as thepatient’s educational process.

And as mentioned earlier, it is important to be com-plete but also succinct. Table 5-1 lists key questions


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that the examiner needs to ask a patient who is com-plaining of pain or change in function in the shouldergirdle. These questions help the clinician begin todiscern if the pain is of mechanical origin.

Screening for Medical ConditionsThat Might Present as ShoulderPain

Musculoskeletal tissues react and respond pre-dictably. When signs and symptoms begin to fall out ofexpected patterns, such as the inability to reproducefamiliar pain with motions or postures, continuousand unrelenting pain, or pain that is greater at rest

than during activity, visceral pathology referring painto the shoulder must be considered and appropriatemedical referral made for additional diagnosticworkup. Visceral pathology such as vascular distur-bances leading to avascular necrosis and the presenceof heart disease, lung tumors, and gallbladder diseasehas a propensity to refer pain to the shoulder. If thepatient has similar complaints at other joints, forexample, bilateral shoulder pain or bilateral wristpain, then rheumatoid disease or one of the rheuma-toid variants must be ruled out. Likewise, a past his-tory of cancer such as lung cancer, breast cancer, orany other metastatic tumor should alert the clinicianthat the current pain complaints might not be associ-ated with the musculoskeletal tissues of the shouldergirdle. Therefore the examiner should always beaware that other disorders might be the source of painwhen the pain pattern, aggravating factors, and easingfactors do not follow recognized musculoskeletal pat-terns. The clinician should be suspicious when thepatient cannot find any position that eases discomfort,has night pain that far exceeds pain during the day orduring his activities, or is complaining of a pain pat-tern that does not follow the typical referral zones formusculoskeletal tissues of the neck or shoulder.Chapter 2 thoroughly detailed the referral pattern forpain from the cervical joints and nerve roots.

Even before beginning the physical examination,answers given by the patient to some of the questionsnoted in Table 5-1 cue the clinician to a potentialcause or causes of the problem and allow him to pri-oritize which special tests might be indicated. In addi-tion, a thorough history directs him to properly planthe examination of the joints and soft tissues that areunder the area of complaint and the tissues that havethe capacity to refer pain to the region.17

Predisposing Factors

Examples of questions that lead the clinician toconsider predisposing factors include “How old areyou?” “What is your occupation?” and “What sports or activ-ities are you involved in?” Answers to these questions helphim focus on the tests and measures that need to beincluded during the physical examination.

It is important to know how old a patient is becausecommon shoulder conditions such as instability androtator cuff pathology are often associated with age.For example, instability would be less likely in apatient under the age of 30 than in a patient of 65.


Table 5-1. Questionnaire for PatientHistory: Shoulder

1. How old are you? What is your occupation?2. In your words, what is the problem?3. How long have you had shoulder pain? How would you

describe it?4. Show me where you have pain. (Consider using a body

chart.) Do you ever have pain, numbness, or tingling in anyother areas? Do you notice any numbness or tingling in thearm or hand? Does your pain extend toward elbow orwrist? Does it stay localized to the shoulder?

5. What position were you in when you were initially hurt?6. Is it difficult to perform activities that require reaching

above shoulder level?7. Describe previous episodes of shoulder pain. How long did

these episodes last?8. What positions or activities increase your pain? What activ-

ities are limited by this problem? Are you able to lie on thatshoulder at night? Does the shoulder pain awaken you atnight?

9. Do you have any neck pain, or do neck movementsincrease your shoulder pain?

10. Is your pain worse in the morning on awakening, or is itworse toward the end of the day? Are you more stiff orsore in the morning as compared with the end of the day?

11. How would you rate your level of activity? What activitiesare limited and why?

12. How would you rate your level of pain?13. Are you currently taking any medications?14. Have you had any surgeries in the past?15. What do you think is the cause of your shoulder pain?16. What goals do you have for treatment results?

Special Questions Related to General Health

1. Have you had any recent weight loss? Do any other jointsin your body have this same type of pain?

2. Does your pain prevent you from sleeping? Is it worse atnight?

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By comparison, frank pathology of the rotator cuff ismore common in patients over 40, whereas the earlierstages of rotator cuff disorders such as tendonitis aremore common in the 25 to 40-age-group.24 The Neerclassification scheme for shoulder impingement illus-trates the cascade of age-related degenerative changesof the rotator cuff that progress from edema and hem-orrhage of the tendon through tendon fibrosis andultimately tendon rupture (Table 5-2). Understandingthese stages and correlating them with the age of thepatient provide more clues.

Another example of shoulder pathology influencedby age is nontraumatic primary “frozen shoulder,” oradhesive capsulitis.7,12 This phenomenon is poorlyunderstood and most often is seen in women from 45 to60 years of age. It is characterized by three stages, any ofwhich might be the first point of contact with the clini-cian. The first stage is the initial freezing stage in which theabrupt loss of motion and excessive pain begin. This isfollowed by the frozen stage in which pain decreases butthe motion is markedly restricted, and then a final stageof thawing during which slow, spontaneous recoveryoccurs, often over a period of 1 to 3 years.22

Finally, it is essential to conduct a careful analysis ofthe patient’s activities of daily living and sport activi-ties, especially those related to overhead activities orrepetitive motions of the upper extremity. Therequirements of the shoulder complex are typicallysport and job specific, so the examiner’s suspicionsbased on this information regarding which movementsand stresses will be painful in the physical examinationand tissues that are most likely compromised are usu-ally accurate. For example:

● Swimming is associated with a high incidence ofimpingement problems, especially in a swim strokesuch as the butterfly and during training with theuse of swim paddles and elastic bands.8 Internalrotation during the stroke increases the compressionof tissues in the suprahumeral space.

● Throwing sports can place a significant stress to theanterior aspect of the glenohumeral joint complex,especially during the late cocking and accelerationphase of throwing.11,29 Pain during these phases isusually felt anteriorly or superiorly as a result ofanterior subluxation of the humerus and impinge-ment of the rotator cuff as the humeral headmigrates superiorly. Throwers also have increasedstresses to the rotator cuff muscles in the cocking,acceleration, and follow-through phases of throw-ing. Pain in the acceleration phase of throwing canbe due to strain on the posterior cuff tendons,whereas the deceleration phase of throwing canresult in pain due to humeral head translation fur-ther increasing rotator cuff strain as a result ofeccentric workload and long head of the biceps ten-don strain. Table 5-3 lists the phases of throwingand selected biomechanics related to clinical prob-lems often noted in the shoulder. Contact sportsincluding football may result in glenohumeral sub-luxation, tensile injuries to the brachial plexus, oracromioclavicular joint injuries. When the patientdescribes contact injuries, the examiner must alsoprepare to assess cervical nerve root and brachialplexus function.

● Tennis may lead to cumulative microtrauma in theposterior rotator cuff tendons and the long head ofthe biceps since the athlete must eccentrically con-trol the lever, now lengthened because of the rac-quet, during the deceleration phase of the stroke.The result is excessive tension to these tissues. Theoverhead activity that occurs during the cockingand acceleration phases also results in the tissues ofthe suprahumeral space being compromised viacompression and renders the articular surface ofthe tendons susceptible to internal impingement.

● Weight lifting practiced with poor technique andweak scapulothoracic muscles places the tissues ofthe suprahumeral space in a compromised posi-tion while performing upper extremity elevation


Table 5-2. The Neer Classification Scheme for Shoulder Impingement

Stage Age Clinical Course TreatmentI: Edema and hemorrhage <25 Reversible ConservativeII: Fibrosis and tendonitis 25-40 Recurrent pain with activity Consider subacromial decompressionIII: Bone spurs and tendon rupture >40 Progressive disability Subacromial decompression and cuff repair

From Neer CS II: Impingement lesions, Clin Orthop 173:70, 1983.

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exercises. Movements such as overhead presses orshoulder raises that maintain the humeral head inthe internally rotated position potentially increasecompression under the coracoacromial arch andshear at the glenohumeral and acromioclavicularjoints. Poor control of heavy weights during benchpress maneuvers stresses the acromioclavicular jointand the anterior and posterior capsular tissues.

● Work-related movements in an industrial settingmay jeopardize arms and shoulders during theirwork tasks. Often, poorly designed workstationscontribute to overuse syndromes not only of the

shoulder but also of the cervical spine and scapu-lothoracic complex. Perhaps even more impor-tantly, the gradual loss of range of motion in thelower cervical and upper thoracic spine, coupledwith loss of glenohumeral motion, as occurs withage, contributes to the inability to position the armscompletely overhead or in the necessary work posi-tion. Full extension of these regions of the spine isnecessary for full shoulder girdle range of motion.This is one of the primary reasons that the forwardhead, rounded shoulder position of the upper quar-ter, which is often accompanied by a slouched,


Table 5-3. Biomechanics of Throwing

Phase Features PainI. Windup and cocking Abduction, extension, and external rotation Pain in the later part of the cocking

phase of the humerus phase is usually felt anteriorly or ● Strong deltoid action in this phase superiorly because of anterior ● Tension placed on the anterior joint structures subluxation of the humerus and ● Supraspinatus provides a stabilizing force through its impingement of the rotator cuff,

action in compressing the humeral head in the glenoid and the humeral head moves superiorly.● Infraspinatus and teres minor maintain humeral head in

fossa through inferior directed forces and also provide concentric contraction

● Subscapularis, aided by the pectoralis major, restricts the terminal external rotation of this first phase through eccentric control and helps stabilize head of humerus in glenoid

II. Acceleration phase Complete reversal of above motion that begins with Pain in the acceleration phase is often internal rotation caused by strain on the posterior cuff

● Internal rotators, notably the subscapularis and pectoralis tendons. Pain in the elbow is caused by major, provide the force valgus stress.

● Eccentric contraction of posterior cuff muscles● Latissimus dorsi, serratus anterior, and triceps provide

additional force through concentric activity● Very strong contraction of the serratus anterior,

trapezius, rhomboids, and levator scapulae, implying that scapular stabilization is essential during this phase

● Large valgus stress at the elbow

III. Deceleration and Strong activity of the rotator cuff to slow the arm down Pain in the deceleration phase may be follow-through phase as motion is completed caused by humeral head translation,

● Subscapularis continues to rotate internally rotator cuff strain, and long head of● Posterior cuff works to decelerate the arm and the biceps tendon strain.

maintain the humeral head within the glenoid; the posterior cuff muscles are the key stabilizing force resisting glenohumeral distraction and anterior subluxation forces

● Supraspinatus works to keep head of humerus compressed to glenoid

● Biceps acts eccentrically to control the rate of elbow extension; supinator acts to eccentrically control the rapidly pronating forearm

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kyphotic posture, is a contributing factor to thedevelopment of impingement syndromes. Whenthese types of postural changes are coupled withweakness and fatigue of scapular muscles such asthe serratus anterior and trapezius in conjunctionwith weakness of the abdominal wall, tissues in thesuprahumeral space have an even greater potentialfor compromise (see Chapters 3 and 6).

Mechanism of Injury

Answers to questions such as “What position were youin when you were initially hurt?” and responses to state-ments such as “Describe previous episodes of your shoulderpain and tell me how long the episodes have lasted” allow theexaminer to begin analyzing whether increased com-pression, tension, or shear stresses may haveoccurred or are recurring. Does the patient describeeither a fall on the point of the shoulder that resultsin damage to the coracoclavicular ligaments andacromioclavicular joint separation, or a fall on theoutstretched hand (a FOOSH injury) (Figure 5-1)?Either can cause a potential fracture to the humerus,scapula, or clavicle or result in significant trauma tothe soft tissues of the shoulder. Falls also may resultin subluxations of either the acromioclavicular jointor the glenohumeral joint. Landing on the point ofthe shoulder can completely disrupt the coracocla-vicular ligaments (conoid and trapezoid), which arethe key support ligaments of the acromioclavicular

joint, or result in significant trauma to the rotatorcuff tendons over the greater tuberosity, which maycause tendon rupture. Likewise, falling on the elbowmay violently drive the humerus superiorly into thesuprahumeral space and result in mechanical traumato the glenohumeral joint capsule, rotator cuff ten-dons, and subacromial bursa.

Was there excessive motion that put the shoulderinto an extreme range of motion? Does the patientnow feel a “giving away” sensation with movement?Did the patient feel the shoulder “come out”? One ofthe most common mechanisms of injury resulting inanterior instability of the shoulder is forced abductionand external rotation of the glenohumeral joint,which stresses the joint capsule, the labrum, and theinferior glenohumeral ligaments (Figure 5-2).

Pain Location and AssociatedSymptoms

Statements such as “Show me where you have pain” andquestions such as “Do you notice any numbness or tingling inthe arm or hand?” “Does your pain extend toward the elbow orwrist?” “Does your pain stay localized to the shoulder?” “Doyou have any neck pain or does neck pain reproduce your shoul-der discomfort?” and “Do you feel your shoulder ‘gives out’?”all provide key information that ultimately directs thelevel of scrutiny of the physical examination. Forexample, instability of the glenohumeral joint can alsocompromise the brachial plexus as it courses through


Figure 5-1. Shoulder injury can occur viaa fall on the point of the shoulder that resultsin damage to the coracoclavicular ligamentsand acromioclavicular joint separation, or afall on the outstretched hand (FOOSHinjury), as illustrated here, that results infracture about the glenohumeral joint.

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the axilla. This results in a patient’s complaints oftransient numbness in the arm or hand, a “dead” feel-ing in the arm with certain movements, or paresthesia.The examiner needs to visualize how the head of thehumerus could compromise the brachial plexus if itassumes a more anterior and inferior position with dif-ferent postures or movements or how the brachialplexus might have been compromised during thetrauma of the injury.

Clinicians must recognize the potential for periph-eral nerve injury secondary to dislocation of the

glenohumeral joint. For example, the axillary nerve,which courses around the neck of the humerus withthe posterior humeral circumflex artery, can beinjured with a glenohumeral dislocation. Injury to theaxillary nerve may result in paralysis or weakness ofthe deltoid and teres minor muscles. Other terminalbranches of the brachial plexus, such as the musculo-cutaneous and radial nerves, potentially may be com-promised by the inferior position of the head of thehumerus, which can occur with dislocation (seeChapter 2). Therefore when there is a history of dislo-cation, the examiner is prepared to clinically assess themuscles supplied by the terminal branches of thebrachial plexus.

When instability is suspected, the clinician will clarifywhether or not there was a traumatic event, the positionsand motions in which symptoms are reproduced or theshoulder feels “unstable,” and whether or not the patientcan voluntarily sublux or dislocate his glenohumeraljoint. A wide range of shoulder instabilities exist, fromthe TUBS type (traumatic onset in a unilateral direction,often causing a Bankart lesion and optimally treatedwith surgery) to the AMBRI type (atraumatic etiologywith multidirectional instability pattern bilaterally, oftenresponsive to rehabilitation, and if surgery is indicated,an inferior capsular shift procedure is commonly used).If the history leads the examiner to suspect gleno-humeral joint instability, he performs several tests in thecourse of the physical examination.

The examiner needs to carefully determine thearea of pain. It is one of the most important pieces ofinformation to be ascertained. The location of painmay indicate that the structures have been injuredand alert him to stresses that might be poorly toler-ated during the physical examination (Figure 5-3,A and B). For example, pain felt at the region of thedeltoid insertion (an area within the C5 dermatome)is often a referred pain pattern from lesions of therotator cuff tendons. Problems of the glenohumeraljoint termed capsulitis refer pain along the C5 and C6dermatomes, which include the area of skin over thedeltoid insertion and the lateral border of the armand forearm. Note that since many of the tissues ofthe shoulder are derived from the fifth and sixth cer-vical cord segments, referral of pain to the arm andforearm is common, whereas referral to the handfrom lesions of the shoulder is less common.Acromioclavicular joint problems typically remainlocalized to the top of the shoulder region becausethe acromioclavicular joint is derived from the thirdand fourth cervical cord segments.


Figure 5-2. Forced external rotation in an abductedposition can damage the anterior aspect of the gleno-humeral joint capsule and the inferior glenohumeral lig-ament complex. Such injury can occur during anafternoon touch football match.

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Patients with multidirectional instabilities of thehumerus on the glenoid typically complain of diffuseshoulder pain with global muscle soreness about theshoulder girdle. This is in contrast to unidirectionalinstabilities that characteristically result in complaintsof pain on the opposite side of the instability. Forexample, the patient with anterior instability will oftendescribe soreness and aching of the shoulder posteri-orly, as well as being tender to palpation over theregion of the anterior glenoid.

Aggravating Factors

Questions that assess the nociceptive mechanicsinclude “Is it difficult to perform activities that require reachingabove the shoulder level?” “What positions or activities increaseyour pain?” “What activities are limited by this problem?” and“Are you able to lie on that shoulder at night?” When answer-ing these questions, the patient has an opportunity todescribe those positions, movements, or activities thatreproduce familiar pain in the shoulder complex.Based on an in-depth understanding of the clinical

anatomy of the region, the examiner can begin to visu-alize how compression, tension, and shear stressespotentially compromise the musculoskeletal tissues inthe positions or movements the patient describes.

Many patients with shoulder disorders complainabout an increase in pain when they attempt to sleepon the side of the shoulder disorder. This is especiallycommon in late stage adhesive capsulitis disorders androtator cuff problems. In both cases, the tissues aremarkedly irritable, and the combination of no move-ment, which promotes stasis, and pressure from lyingon the shoulder increases pain and results in increas-ing the referred pain pattern along the lateral aspect ofthe arm.

Pain Behavior and Intensity

Questions such as “On a scale of 0 to 10 with 10 beingthe most discomfort you have had with this particular problem,what level of pain are you currently experiencing?” and “Is yourpain greater in the morning than in the evening?” provide theclinician with the patient’s own interpretation of his


Figure 5-3. A and B, Patients with cervical nerve root problems often need to support the shoul-der girdle in some way in order to minimize tensile stresses through the brachial plexus and cervicalnerve root complex.

BA

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pain. Mechanical disorders of the musculoskeletal sys-tem typically feature pain patterns that are aggravatedwith increased compression, tension, and shearstresses to the injured tissues (mechanical stimulationof the nociceptive system) or continued activation ofthe nociceptive system by chemical irritation (i.e., achange in the chemical milieu as a result of tissueinjury). For example, pain felt in the morning whenthe patient awakens that eases as the day progresses istypical for injured tissues that have an associatedinflammatory process (Figure 5-4). With rest and sleepin the recumbent position, there is no muscle pumpingaction to decrease fluid stasis and therefore the chem-ical environment associated with stasis results in chem-ical activation or depolarization of the nociceptivesystem. When we get up and begin to move, musclecontraction around the injured tissues creates pres-sures that restore microcirculation and lymphdrainage. This results in a change in the chemical

environment of the injured region. The Blazina clas-sification of pain, presented in Table 5-4, offers a wayto assess the severity of the complaint.

Assessment of FunctionalLimitations

Patients seek help for their musculoskeletal prob-lems for one of two reasons: pain or a problem thatis now compromising desired function. Questionssuch as “What activities are limited because of this prob-lem?” or “On a scale of 0 to 10 with 0 being no limitationto activity and 10 representing all activity that you normallydo, what level of activity are you at because of this problem?”begin to provide the clinician with informationregarding the patient’s perception of his problemand how this problem is affecting his life. Answers tothese types of questions need to be correlated withself-reports of pain because a reasonable relation-ship between pain intensity and compromise tofunction will exist.

Several tools designed to provide a convenient wayto systematically document shoulder function areavailable. We refer the reader to two different shoulderquestionnaires that are reliable and are more sensitiveto change in patients with shoulder pain than ageneric questionnaire.2 The tools are the SimpleShoulder Test (SST) and the Shoulder Pain andDisability Index (SPADI).

The SST is a self-report questionnaire that takesapproximately 5 to 10 minutes to complete and con-sists of 12 yes or no questions that assess functional lim-itations caused by shoulder pathology.18 The questionsfocus on an individual’s ability to tolerate or performmultiple activities of daily living.

The second outcome tool is the SPADI.10,31 This isa self-report questionnaire that consists of two sub-scales identifying pain and projecting disability. The


Sleep

Sleep

PMAM

PAIN(swelling)

PAIN(swelling)

PMAM

Figure 5-4. Pain is experienced in different ways dur-ing the AM and PM time periods as shown in this graphi-cal representation of pain behavior. Pain that is greaterin the morning but decreases as we move the injuredregion is suggestive of inflammatory conditions andswelling of the injured tissues. Such a reaction indicatesa chemical cycle of pain (top graph). Pain that is greatertoward the end of the day suggests muscular fatigue anda resultant loss of neuromuscular control of the affectedregions that cause mechanical overload in the connectivetissue elements. Such reaction indicates a mechanore-ceptor cycle of pain (bottom graph).

Table 5-4. The Blazina Classificationof Pain

Grade I: Pain with activityGrade II: Pain during and after activity, but not disablingGrade III: Pain during and after activity and disablingGrade IV: Pain with activities of daily living

Data from Blazina ME et al: Jumper’s knee, Orthop Clin North Am 4(3):665,1973.

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pain dimension is measured based on the severity ofan individual’s pain, whereas the disability dimensionis measured based on the degree of difficulty an indi-vidual has with various activities of daily living thatrequire upper extremity use. The time needed to com-plete this 13-item index is also 5 to 10 minutes. Bothtools can easily be used to assess a patient’s own per-ception of the pain and functional limitations he nowhas because of his shoulder condition.

The Patient’s Description of the Problem

Ask the patient, “What do you think is the cause of thepain?” or “What goals do you have as a result of treatment?”His analysis of the cause of his pain provides you withadditional information regarding nociceptive mechan-ics. For example, patients often talk about “pressure,”“grinding” or “slipping,” or a fear of different posi-tions. If the patient states that he does not know whatthe problem is, encourage him to describe his ownshoulder in his terms. The intent is to further yourunderstanding of how the patient views his problem.This information is used to more tightly focus thephysical examination.

Asking the patient to articulate his goals for treat-ment establishes his role in the total rehabilitationprocess. In addition, it allows the clinician to begindetermining whether these goals are realistic whencompared with the results of the examination. Injuredconnective tissues are repaired rather than regenerated.Injured tissues and those tissues with age-related degen-erative changes have newly imposed mechanical stresslimits that imply what activities of daily living and sportmay need to be modified (see Chapters 1 and 6).

To review, three essential pieces of informationneed to be gained from the questions asked. They arethe pathomechanics, the pain syndrome that is beingpresented, and the presence or absence of stability.Whatever the format of the questions, each questionneeds to be asked within a logical order so that thepatient can follow the sequence of this history. Whenthe patient is following the line of questioning, he canbetter relate one question to the other. Furthermore, alogical line of questioning gives the clinician opportu-nities to show the patient how one piece of informa-tion begins to correlate with another. Thus theteaching process for self-management of the conditionhas already begun.

Physical Examination

Carry out the physical examination in a mannerthat does not require the patient to change positionscontinuously. Organize it in logical fashion so that sub-sequent portions of the physical examination build onthe results of tests immediately completed and thepatient history. The challenge is to be thorough yetavoid unnecessary redundancy. If the examiner is ableto conclude from the history the pathomechanics, syn-drome classification, and presence or absence of sta-bility, the essential tests needed in the active, passive,resisted, and palpation sequences of the examination,coupled with observation of static and dynamic pos-tures, become more obvious. We will review and dis-cuss each part of the sequence of the physicalexamination that we typically use here.

Observation and Inspection

The physical examination begins with the patient inthe standing position (Table 5-5). Observation of thepatient presenting with shoulder complaints includes thehead, neck, shoulder girdle, thoracic spine, and abdom-inal wall. Key aspects of the observation portion of thephysical examination are noted in Table 5-6. Inspectingthe posture in the sagittal plane is the best way to assessfor the presence of the forward head, rounded shoulderposture, which provides an excellent indication of thefunction of the abdominal wall musculature.

Frontal plane postural assessment often revealsasymmetry associated with handedness patterns.Typically the dominant side shows slightly greaterhypertrophy and a lower riding scapula on the ribcage. Noting the levels of the iliac crests, posteriorsuperior iliac spines, and the lumbar waist angle alsoprovides information regarding the overall frontalplane posture.

Clarify bruises or scars and clearly understand pastsurgeries to any region of the upper quarter. Compare


Table 5-5. Sequence of PhysicalExamination: Standing Position

1. Have patient place hands on hips.2. Observe static upper quarter and trunk posture.3. Manipulate active physiological motions with overpressure if

indicated.

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the contour of the shoulders bilaterally, giving specialattention to the humeral heads on both sides of thebody, the acromioclavicular joints, and the musclegirth in the infraspinatus fossa. The humeral headinspection is especially important because even a slightinferior displacement of a subluxed humeral head andthe resultant sulcus sign over the suprahumeral spacecan be detected in lean individuals. We prefer to lookat the resting posture of the shoulder girdle with thepatient placing his hands on his hips. Scapula positionsand the detection of shoulder girdle muscle atrophyespecially over the infraspinatus fossa are much easierto compare bilaterally from this position (Figure 5-5).

Finally, how the individual is holding the upperextremity is instructive. Note how the individual pro-tects or supports the upper extremity and the mannerin which he carries his upper quarter. This can revealhow fearful he might be during further aspects of theexamination. For example, shoulder-hand syndromesare extremely complex disorders accompanied byvasomotor changes in the upper quarter and extremeguarding and fear of movement of the completeupper extremity. Be cognizant of the potential for suchsyndromes with any type of trauma or surgery associ-ated with the upper extremity.

Active Motion

The best way to begin the provocation portion of thephysical examination is to start with active motions. Weprefer to carry out the active motions with the patient inthe standing position (Table 5-7). Active motions pro-vide information regarding the patient’s ability and will-ingness to move. During the active motion examination

of the shoulder girdle, look at the glenohumeralmotion, the scapulothoracic motion, and the motion ofthe cervical and thoracic spine. As mentioned through-out Chapter 4, the ability to elevate the arm completelyoverhead is dependent on full mobility and strength forall shoulder girdle articulations, as well as for cervicalspine and upper thoracic spine extension. During anymotion, clarify if familiar pain is reproduced and thelocation of that particular pain.

The sequence of active motions is noted in Table 5-7.A quick screen of the cervical spine begins activemotion assessment. The patient is asked to move thehead and neck into the forward (Figure 5-6, A) and


Table 5-6. Observation and Inspection:Key Points

1. Check sagittal and frontal plane postural relationships ofhead, neck, shoulder girdle, thorax, and abdominal wall.

2. Observe posture of arm and shoulder girdle and position ofscapula on rib cage.

3. Check symmetry.4. Check the relationship of clavicle to acromion process.5. Observe arm swing.6. Check for evidence of atrophy.7. Check for scars and bruises.8. Observe contour: does the patient tend to support arm or

hold arm close to chest?9. Always compare bilaterally.

Table 5-7. Assessment of Active Motion

1. Clearing of cervical spine2. Glenohumeral assessment: consider having the patient start

by simultaneously moving both armsFlexion, extensionAbduction, adductionInternal and external rotationHorizontal adduction“Scaption,” or movement with arm in internal and external

rotation3. Scapula: Elevation, depression, protraction, retraction

Figure 5-5. The hands on hips position makes it easierto detect the various shoulder asymmetries, such as thoseaffecting the scapular position or muscle atrophy.

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backward (Figure 5-6, B) bending quadrants, and theexaminer can overpressure these motions to see ifshoulder pain is reproduced. If the examiner suspectsthat the upper quarter pain is from cervical spineinvolvement, then a complete cervical spine examina-tion is indicated.

Now active movement of the shoulder girdle can beassessed. Elevation is the terminology typically used forany movement of the arm overhead and includes thecontributions for all articulations of the shoulder com-plex. Such motion can occur in the sagittal (pure flex-ion motion) or frontal (pure abduction) cardinalplanes, but from a functional standpoint, elevation ofthe arm typically occurs in an arc that lies somewherebetween the frontal and sagittal planes. We typicallyhave the patient elevate the arm overhead severaltimes and in varying positions between the sagittal andfrontal planes. The patient is asked to raise his armsforward as high as he can several times in differentportions of the arc between the sagittal plane andfrontal plane. The plane midway between the sagittaland frontal planes is referred to as the scaption plane andis the approximate plane of the scapula as it sits on thethorax. We then ask the patient to place his shouldersin varying degrees of internal and external rotation ashe elevates the arm in order to assess how symptomsmight be affected (Figure 5-7, A-E ). Note any appre-hension to motion and points in the range of motion

that reproduce familiar pain. We do not hesitate toapply gentle overpressure at the patient’s limits ofactive arm elevation because we now have the abilityto clarify the effects of increased compression, tension,or shear to the motion with simple adjustments ofhand position or direction of force application. Theranges of motion can then be recorded, with 175 to180 degrees of motion being the normal ranges ofoverhead motion.

Acromioclavicular joint pain is typically increasedat the extremes of shoulder range of motion, so over-pressure to arm elevation at 170 to 180 degrees mayprovoke this joint. Likewise, horizontally adductingthe glenohumeral joint fully eventually begins to forcethe scapula into protraction, and further overpressureof this maneuver increases stress to the acromioclavic-ular joint and increases compression of the soft tissuesbetween the humerus and coracoid process. Thereforethe examiner needs to apply overpressure to activemotions using several different lines of force, all thetime visualizing the tissues that are simultaneouslybeing compressed or that are subject to shear andtension with such maneuvers.

During active elevation of the arm overhead thepresence of a painful arc may be revealed. Althoughnot as valuable a sign with an acutely painful shoul-der, a painful arc has been defined as an arc ofmotion in which there is a beginning range without


Figure 5-6. Ask the patient to move the cervical spine in the forward bending and backward bend-ing quadrants. In A, apply overpressure to the forward bending quadrant, and in B, apply over-pressure to the backward bending quadrant.

BA

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pain (Figure 5-8, A), followed by a portion of the arcwith pain (Figure 5-8, B), whereas the last part of thearc is without pain (Figure 5-8, C).4,23,25 Nopain–pain–no pain constitutes the classic painful arc asthe arm moves from a position at the side of the bodyto complete elevation and has been attributed to irri-tation of tissues in the suprahumeral space, which aremaximally stressed in compression during the middlerange of elevation as the tuberosity of the humerusengages with the undersurface of the coracoacromialarch. The structures potentially irritated include thesupraspinatus, the infraspinatus, the long head of thebiceps tendon, the subacromial bursa, and the supe-rior aspect of the glenohumeral joint capsule.

Notice the difference between a painful arc due toimpingement and loss of the arc of motion because ofsuspected capsular restriction. In a capsular restrictionpain and motion limitation would begin at some point

in the arc and progressively become more problematicwithout an easing of pain toward the end of themotion. The pattern of the capsular restriction is thusno pain followed by increasing pain, as compared with apainful arc where we see pain toward the middle ofthe arc of motion.

All motions of lifting the arm overhead includescapulothoracic motion that is smooth and relativelysymmetrical without winging from the rib cage.The pattern of scapular motion is actually quiteunpredictable as it moves in varying amounts ofupward rotation and protraction depending where inthe arc between the sagittal and frontal plane the armis elevating. The clinician also needs to realize that themajority of scapular motion occurs after humeral ele-vation exceeds approximately 90 degrees and it is onlyin coronal plane motion that the scapula begins itsrotation at lower degrees of elevation.5


B CA

ED

Figure 5-7. A, To demonstrate activeglenohumeral and scapulothoracicmotion in the scaption plane, ask thepatient to begin by elevating thehumerus in the scaption plane, B, andcomplete the motion by elevating thescapula. C, Then with the humerus at90 degrees of abduction the patient isasked to perform complete external rota-tion, D and E, and internal rotation.The quality of motion and apprehen-sion is observed.

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The range of motion for active internal rotation isnormally 70 degrees, whereas that of active externalrotation is approximately 90 degrees. Although it oftenis suggested that having the patient reach behind hislow back and attempt to bring his hand up the spine isan excellent way to assess internal rotation, such amotion results in so much scapular movement on thethorax that the value of assessing internal rotation inthis way is questionable. It is much easier, and perhapshas greater functional implications, to assess activerotation in these two ways:

1. With the arm at the side and elbow flexed to 90degrees and then observing active internal andexternal rotation

2. With the humerus abducted in the coronal plane to

approximately 90 degrees and then asking thepatient to internally and externally rotate his shoul-ders. From this position it is very easy to see howearly the scapula comes into play during externalrotation and whether or not there is a significantdifference in the scapulothoracic and gleno-humeral motions when comparing the two sides(Figure 5-9, A-C ).

If overpressure is applied to the rotations of theglenohumeral joint at this point, special attentionneeds to be paid to potential subluxations. The patientmay feel especially vulnerable with overpressure inexternal rotation, so do not attempt to push throughany muscle guarding that may be present. Consider


B

C

A

Figure 5-8. The typical painful arc of motionthat signifies capsular restriction and impinge-ment begins at 0 degrees of active abduction toapproximately 60 degrees A, and is painless. B, As the arm moves from 60-120 degreesthere is a scapular substitution that accompa-nies humeral abduction that is designed to min-imize suprahumeral compression and this arc ispainful. C, The arc from 120 degrees to end ofrange of abduction is again painless.

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stabilizing the anterior aspect of the humerus and gle-noid if overpressure in external rotation is applied atthis point in the examination. Subtly removing andreapplying this stabilization force over the anterioraspect of the glenohumeral joint offers significant cluesregarding the presence or absence of joint stability.

During all requested movements, it is essential toview scapular motion and humeral motion simultane-ously. Assess whether the overhead motion attemptedby the patient is primarily scapulothoracic motion thatmight occur with adhesive capsulitis or rotator cuffproblems. With these two clinical problems, very littlehumeral motion occurs on the glenoid, and instead,the arm moves upward or out to the side primarily bymotion of the scapula on the thorax. The scapulotho-racic articulation is quite mobile in all planes, and theclinician can be misled into thinking that more gleno-humeral motion is present than is actually available.The final portion of the active motion tests look at iso-lated scapular motion, such as elevation, retraction,depression, and protraction, and the effect thesemotions may have on the familiar pain.

On completion of the assessment of the activemotions of the shoulder girdle, we have a good ideaof the pain location, where throughout the ranges thepatient has the most difficulty (due to pain, weakness,motion limitation, or feeling of instability), and theease in which the symptoms can be provoked. Wehave the patient repeat these active motions numer-ous times because the self-report of any difficultiesexperienced during active ranges needs to be consis-tent and reproducible to be of value. Subsequent por-tions of the examination use the information alreadygleaned to place selected stresses into the various tis-sues in order to provide further clarification of thepainful syndrome.

Passive Motion Assessment andPassive Provocational Tests

At this point we ask the patient to be seated.Typically we conduct several of the passive testsdescribed in this section from the seated position(Table 5-8) and then conduct the remaining passive


B

C

A

Figure 5-9. Assess glenohumeral rotation intwo ways: A, Examine the supine patient withan extremely painful shoulder with the involvedarm in a neutral position. B and C, Use a posi-tion that begins to approximate functionalmotion where the humerus is abducted toapproximately 90 degrees and ask the patientto externally, B, and internally, C, rotate fromthat position. This is the best position to seehow quickly the scapulothoracic articulationmoves and how much of the rotation is actuallyglenohumeral versus scapulothoracic.

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tests from the supine position. If necessary, the side-lying or prone positions can also be used to furthersubstantiate findings from the seated or supinepositions.

The passive tests are designed primarily to provokefamiliar pain through carefully applied compression,tensile, or shear stresses to the glenohumeral structures.Most passive tests for the musculoskeletal system takeadvantage of an understanding of the three dimen-sional relationships of anatomical structures, and thusmany of the tissues can be passively prepositioned sothat the examiner can apply a passive force and assessthe response. Thus passive tests are not limited to assess-ing the connective tissues, such as the joint capsule andligaments, but can also be used in physical examinationof the shoulder to assess muscle-tendon tissues.

We feel that the passive tests are the most importantpart of the physical examination for mechanicalshoulder pain. Although there are many different pas-sive tests for physical examination of the shoulder, twokey items are important to consider regardless of thetest used:

1. Recognize exactly where the forces you apply ulti-mately converge in the region and what movementsof the articulation might occur with the applicationof such forces. It is essential to have the ability tovisualize the anatomy and understand exactlywhich force or combinations of forces are beingapplied to tissues of the region.

2. Apply overpressure carefully during the test andnote the end feel (e.g., the feeling imparted to theexaminer’s hands during the passive test) and therelationship of that end feel to the patient’sresponse. Does pain occur before, during, or afteryour hands meet resistance? This information isimportant for examination purposes and whenconsidering and planning the treatment process.

The examiner has most likely decided whether ornot stability is a question from the informationobtained in the patient history and the active tests.Further corroboration can be gained using a series ofpassive tests from the seated position.

The first test we prefer to conduct is the sulcus test,which assesses inferior glenohumeral joint instability(Figure 5-10). In this test the patient is seated with thearm comfortably at the side. The examiner palpatesthe suprahumeral space with one finger, and the oppo-site hand applies an inferiorly directed force throughthe long axis of the humerus. A positive sulcus testresults in a “gaping” at the suprahumeral spacebecause of excessive inferior translation of the head ofthe humerus.6,19

After repeating the sulcus test, and thus developingthe ability to visualize the anatomical relationships ofthe patient’s scapulohumeral interface, we perform theload and shift test (Figure 5-11, A-C ).9 In this test thepatient is seated with his hand resting on his thigh.The examiner grasps the humeral head and com-presses it into the glenoid fossa, thus seating the headof the humerus within the glenoid. This is consideredthe “load” portion of the load and shift test. From thispoint the examiner attempts to translate the head ofthe humerus anteriorly and posteriorly, notinghumeral motion, and ascertains whether the humeralhead is clicking over the glenoid rim. Because of theloading portion of the examination, less movementwould be expected in this test than the next test thatwe perform: the drawer test.

Drawer tests also assess translation of the humeralhead. Normally translation is equal anteriorly andposteriorly and is best assessed with the arm toward 90degrees abduction and neutral rotation (Figure 5-11,D-E ). Carefully assess motion and whether thehumeral head, if unstable, clicks over the glenoid rimduring the test. Again, it is important to compare thefirst with the opposite shoulder. If it is difficult to holdthe arm and apply the translatory stresses, or if exces-sive muscle guarding develops as the arm is passivelybrought out to the start position, the test can easily bedone when the patient is moved to the supine position.

Palpation

Although some clinicians prefer to wait until theend of the examination to conduct a palpationsequence, the examination process has alreadyrevealed a significant amount of information from thehistory, the active tests, and the beginning battery of


Table 5-8. Sequence of PhysicalExamination: Seated Position

Sulcus testLoad and shift testDrawer testsPalpationNeuromuscular resisted testsImpingement testsAssessing generalized connective tissue laxity

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stability tests. Thus the information that can be gainedfrom conducting a palpation examination at this pointis valuable because it confirms findings that havealready been arrived at and helps provide the focus forthe remaining portion of the physical examination.

Palpation is usually performed to detect tender-ness in underlying musculoskeletal structures but alsoneeds to be performed to assess for the presence ofmuscle spasm, nodules, temperature and swelling,and changes in contour when the two sides are com-pared. We prefer to start away from the area of painand then move toward the existing complaint. Table5-9 lists the essential areas for palpation in the shoul-der examination. The examiner cradles the humerusand the arm as it is moved to varying positions inorder to palpate and repalpate the shoulder. We payparticular attention to the region over the anteriorglenoid, the complete surfaces of the tuberosities, thesuprahumeral space, and the acromioclavicular joint.We typically use the following sequence whenpalpating the shoulder:

AnteriorKey palpations on the anterior aspect of the shoul-

der include the acromioclavicular joint and along thelength of the clavicle. The clavicle usually ridesslightly higher than the acromion and can be checkedto reveal whether or not a subluxation or dislocation of

the acromioclavicular joint is present. Old fractures ofthe clavicle may have formed a large, bony callus,which can mechanically compromise the neurovascu-lar bundle as it travels between the clavicle and firstrib. Acromioclavicular joint arthritis can manifest aspain with palpation over the joint line. At this point inthe examination, the clavicle also can be gently movedinferiorly or posteriorly to assess the response of theacromioclavicular joint to accessory movement. Theundersurface of the acromioclavicular joint is oftenassociated with compromise to the rotator cuff ten-dons, contributing to impingement syndrome. Thesternoclavicular joint region can be palpated as well,although its involvement in shoulder joint pathologiesis significantly less likely than involvement of theacromioclavicular joint.

The anterior aspect of the glenoid labrum isanother important structure to palpate (Figure 5-12,A and B). The glenoid labrum is often tender to pal-pation in patients with subluxation or instabilityproblems of the glenohumeral joint. From this pointin the palpation, the examiner can move to theregion of the lesser tuberosity, which serves as theinsertion for the subscapularis muscle, and then justlaterally to the bicipital groove. The examination ofthe anterior structures is usually concluded with thesoft tissues of the anterior axillary fold and the supra-clavicular tissues.


Figure 5-10. Perform the sulcus test toassess inferior glenohumeral joint insta-bility with the patient seated with thearm comfortably at the side. Palpate thesuprahumeral space with one finger, anduse the opposite hand to apply an inferi-orly directed force through the long axisof the humerus. A positive result on thesulcus test is marked by a “gaping” at thesuprahumeral space because of excessiveinferior translation of the head of thehumerus.

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B CA

ED

Figure 5-11. In the load and shift test, A, first the examiner uses his bottom hand and body to exerta superior and medial force along the humerus to increase compression at or “seat” the gleno-humeral joint. B, The opposite hand cups the humeral head, and then the thumb and middle fingercreate a transitional force that moves the head of the humerus anteriorly, C, and posteriorly. Thedrawer test examines passive mobility or stability of the glenohumeral joint. A positive finding allowsthe examiner to feel the humeral head rise up on the glenoid labrum, often producing an audibleclick. This can be interpreted as one or a combination of capsular instability, a labral tear, ordetachment of the glenoid labrum. Other techniques, D and E, can be used to assess the integrityof the glenoid labrum. Such techniques use the humerus and the base of the hand to specificallydirect the desired force to the head of the humerus.

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Many tests have been described for assessing labraldefects, and several are illustrated here that are useful inidentifying labral problems, including the “clunk test”1

(Figure 5-13, A and B), the Kibler test15 (Figure 5-14),and the O’Brien test,28 or active compression test (Figure5-15, A and B). Further examination via arthroscopy,

magnetic resonance imaging, or CT arthrography isoften necessary to make the definitive diagnosis.

Lateral and PosteriorOne of the key areas for palpation is the

suprahumeral space. Several key tissues, notably theglenohumeral joint capsule, the supraspinatus andinfraspinatus tendons, the long head of the biceps ten-don, and the subacromial bursa, lie in this region. Theexaminer needs to carefully palpate the region imme-diately under the acromion and continue the palpa-tion inferiorly over the complete greater tuberosity. Weprefer to place the humerus in various degrees ofexternal and internal rotation and then palpate thegreater tuberosity as increasing areas of the cuff andbursa become exposed with this technique.

Table 5-9. Key Areas for Palpation:Shoulder Region

Acromioclavicular jointGreater and lesser tuberosities of humerusBicipital groove for long head of the bicepsAreas of bursae, especially suprahumeral spaceAnterior axillary foldAnterior labral regionSupraclavicular soft tissueAny other areas on basis of examination

B

A

Figure 5-12. Palpation of the ante-rior aspect of the glenoid labrum canbe done with, A, the patient in asupine position, or B, the patientseated. This is an important palpationbecause tenderness in this region iscommon in patients with subluxationor instability problems of the gleno-humeral joint. Tenderness also mayindicate anterior labral lesions.

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The supraspinatus and infraspinatus muscles canthen be palpated in their respective fossae. We concludethe examination of the posterior structures by assessingthe soft tissues of the posterior axillary fold and theparaspinal muscles. Tenderness over the superomedialcorner of the scapula is often found in patients withrotator cuff tendonitis. One potential reason for this isthe mechanical linkage between the supraspinatus andlevator scapulae muscles at the medial aspect of thesupraspinous fossa (see Chapter 3).

Muscle-Tendon and NeuromuscularExamination via Resisted Tests

Once the information from the patient history isconfirmed via palpation and stability tests and withthe patient still seated, we proceed with tests that areintended to answer two questions:

1. Do contractions of the muscles associated with theshoulder girdle reproduce familiar pain?

2. Are there any neural conduction problems?

Resisted tests were first described by Cyriax as ameans to discern muscle-tendon lesions from lesions ofthe inert tissues.4 While instructive for reviewing thefunctional anatomy of the shoulder, it is probably notpossible to completely isolate the muscle-tendon unitsfrom the connective tissue structures. As noted in

Chapter 3, the attachments of the rotator cuff musclesare not simply connected to the tuberosities of thehumerus, but rather via a blending with the gleno-humeral joint capsule. Likewise, the muscle tissues areintimately related to the fascial networks of the


BAFigure 5-13. The “Clunk test” is performed by positioning a supine patient’s shoulder in 0 degreesabduction and 90 degrees elbow flexion and then slowly A, internally and B, externally rotating thehumerus while maintaining strong joint compression through the long axis of the humerus. A “catch-ing or clunking” of the humerus during the rotation is considered to be a positive sign.

Figure 5-14. In the Kibler test, the standing patient hashis hands on his hips, with his thumbs draped over theposterior aspect of the iliac crest. Stabilize the shouldergirdle with one hand and push strongly through the elbowalong the long axis of the humerus while the patientpushes back in the opposite direction. Pain, popping, orclicking in the shoulder is considered a positive sign.

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shoulder, and contraction of the muscle exerts tensilestresses to the fascia and ligaments via direct pull andthrough the broadening effects of the muscle within itsfascial envelope, such as the compartmentalized infra-spinatus muscle.

Despite the limitation of not being able to com-pletely isolate the muscle-tendon unit, screening theshoulder muscles is essential because of the possibil-ity of provoking pain and detecting weakness. Ifweakness is detected, the examiner needs to com-prehensively test the muscles of the shoulder girdle.The motions that should be tested as part of the rou-tine shoulder examination are listed in Table 5-10.We pay particular attention to those tests that canpotentially detect strength or weakness of the cufftendons and whether contraction of the musclesreproduces familiar pain because a large proportionof shoulder pathologies are related to involvementof the rotator cuff.

We do the initial portion of resisted testing with thepatient’s arm at the side and without any movementallowed between the humerus and the scapula. Theintent of such an isometric test is to minimize forceson surrounding capsule or ligamentous structures. Werequest that the patient “hold” the position while the

testing force is being applied rather than encouraginghim to “push against us.” Using the former commandinstead of the latter one ensures that the examiner isin complete control of the test and allows for specificgradations of resistance force to be applied. Figure 5-16,A-F, demonstrates selected tests for the resisted testsportion of the shoulder examination.

Since rotator cuff pathology is so common, specialattention usually is given to assessment of the musclesthat make up this important complex. The supraspinatus


Figure 5-15. Perform the O’Brien or active compression test by having the patient bring the shoul-der to 90 degrees flexion and 15 degrees adduction. A, With the humerus externally rotated (thumbup), resist further shoulder elevation, and B, Repeat the same maneuver with thumb down position.The thumb down position exhibits increased loading of the labrum-biceps tendon complex.Consider the test positive if the thumb up position relieves pain compared to the results in thumbdown position.

BA

Table 5-10. Resisted Tests of the Shoulder

Assess for weakness and reproducibility of symptoms using:Forward flexion in neutralForward flexion with arm forward (Speed’s test)Shoulder extensionShoulder abduction in neutralShoulder abduction in impingement positionShoulder adductionInternal rotationExternal rotationElbow flexionElbow extension

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C

E

A

D

F

B

Figure 5-16. There are a number of resisted tests for examination of the shoulder. Examples include:A, Resisted external rotation from neutral position. B, Resisted external rotation with the arm pre-positioned in internal rotation. Note that this position stretches the infraspinatus and teres minor, andthen asks the muscle to contract strongly from the stretched position. Generally, if more passive pre-stretch is needed to provoke pain with muscle contraction, the lesion is considered to be less severe. C, Impingement test position with the arm forward flexed and internally rotated. The patient is askedto “hold,” and pain with contraction usually incriminates the supraspinatus muscle. D, Speed’s test isan excellent tool to assess the biceps tendon, specifically for the SLAP lesion. The examiner resistsshoulder flexion while the arm is first supinated, and then with it pronated E, while the elbow remainsextended. An even better assessment that uses Speed’s test actively resists an eccentric movement of thearm into extension. This puts increased tension onto the biceps tendon and moves the bone under thetendon. F, Position the shoulder to place maximal stress to the biceps tendon by creating a posterior toanterior force to the humeral head with the left hand while the right hand resists shoulder and elbowflexion. This uses the head of the humerus as a fulcrum, which increases the tensile stress of the bicepstendon. Resisted pronation and supination further stress the tendon and its attachment.

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muscle is often tested using the “empty can” test, inwhich the patient’s arm is abducted to approximately 90degrees without any rotation of the humerus.13 A resist-ance force to abduction is applied, and the arm isbrought forward into the scaption plane while thehumerus is internally rotated (thumb toward the floor asif emptying a can), with resistance to abduction beingapplied once again. Weakness or pain is indicative ofsupraspinatus involvement.

A variation of the empty can test is used to detectcomplete tears of the rotator cuff tendons and isknown as the “drop-arm” test.21 Here the examinerpassively lifts the shoulder to the abducted positionand asks the patient to hold the position and begin toslowly lower the arm to the side. The test is consideredpositive when the patient cannot hold the position orlower the arm slowly and the arm falls back to thepatient’s side.

In our experience simple resisted flexion of theelbow as described by Cyriax rarely elicits pain frominvolvement of the long head of the biceps tendon.This is because lesions of the long head of the bicepstendon are primarily of two types: the SLAP (supe-rior labral anterior to posterior) lesion, which is a par-tial avulsion of the long head of the biceps andsuperior glenoid labrum from the glenoid, and ten-donitis or tenosynovitis as a result of friction of thetendon in the bicipital groove of the humerus. SLAPlesions are among the most complex because they canbe subdivided into four different classifications basedon the extent of the labral and biceps tendon detach-ment.33 One of the best tests to assess the long headof the biceps is to pre-position the shoulder in for-ward flexion and apply resistance to forward flexionin a manner that makes the test an eccentric contrac-tion of the shoulder flexors (Speed’s test). In otherwords, the examiner carefully pushes the patient’sshoulder back toward extension, gently overcomingthe resistance of the shoulder flexors. Further tensioncan be placed through the long head of the biceps bysimultaneously resisting forearm supination duringthe flexion movement, or by passively pre-positioningthe forearm in full pronation for the test. The exam-iner needs to be careful during this test because anabrupt force, or one that is too great, can cause fur-ther injury to the long head of the biceps tendon andthe glenoid labrum.

Performing these tests places a strong tensile stressto the long head of the biceps tendon and moves thehumerus under the tendon. The examiner needs torealize that sometimes it is this movement rather than

the resistance that reproduces shoulder pain; move-ment of the humerus under the tendon creates a fric-tional force between the tendon and the bicipitalgroove. The biceps tendon does not slide in the bicip-ital groove, but rather the bony groove slides under thetendon. Understanding this subtle difference betweenthese mechanics becomes important in developing anexercise program. Patients with a suspected tenosyn-ovitis problem must learn that decreasing motion ofthe affected arm from flexion to extension (such as inrowing exercises, work, or sport) is the best way to restthe injured long head of the biceps tendon, ratherthan simply decreasing the movements of elbowflexion and extension.

Finally, muscle tests can be performed to confirm orrule out any neural conduction problem (see Tables 2-1and 2-2).

Impingement Tests

The patient history, along with results of palpationand resisted tests, provides the examiner with importantinformation about the tissues under the coracoacromialarch. Next, we typically conduct the various impinge-ment tests with the patient in the seated position. Asmentioned in Chapter 4, the examiner’s frame of refer-ence must include both external and internal impinge-ment. We simplify the examinations for these twoconditions by considering external impingement to beprimarily related to the bursal side of the cuff tendonand the intimate association that this side of the tendonhas with the coracoacromial arch and internal impinge-ment to be more closely related to the articular side ofthe tendon and the relationship that this region of thetendon has with the glenoid labrum.

External impingement is recognized as a compo-nent of cuff disorders and frequently, and perhapseven more commonly, a secondary phenomenon asso-ciated with activities or adaptive changes in the con-nective tissues of the glenohumeral joint capsule.Overuse and fatigue related to eccentric overload ofthe rotator cuff muscles resulting in intrinsic fiber fail-ure of the cuff and biceps tendon constitutes the pri-mary etiology in the active, young population(throwers, lifters, workers). The initial failure of thefibers may lead to secondary impingement as externalforces, such as those with throwing, pull the cuff supe-riorly. Patients with anterior instability are also at riskfor impingement because of the architecture of thesubacromial region. Those with loose shoulders or mul-tidirectional instabilities may develop cuff tendonitis


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because of overwork and overstretching of the gleno-humeral joint capsule.

There are several special passive tests for externalimpingement (Figure 5-17, A-D). Pain on forced for-ward flexion in which the greater tuberosity is forcedup against the acromion is often referred to as the Neerimpingement test.26 This test may be varied through anattempt to provoke pain with forced internal rotationof the 90-degree forward flexed arm. We use a com-bination of these tests in which the humerus is forcedup against the acromion with the humerus initially inmaximal external rotation. After the humerus is low-ered away from the arch, it is internally rotated andthen again forced up against the arch. This is repeatedseveral times with the arm internally rotated slightly

more each time until it reaches full internal rotation.Testing in this manner presents a significant portion ofthe greater tuberosity and the bicipital groove to theundersurface of the coracoacromial arch.

Internal impingement is a phenomenon most oftenfound in shoulders that exhibit laxity, whether thatlaxity is congenital or, more commonly, a result ofacquired laxity seen in overhead athletes. An abduc-tion and external rotation motion with a lax shoulderresults in the humerus subluxing anteriorly. When thissubluxation occurs, the greater tuberosity impinges onthe posterior-superior aspect of the glenoid rim. Thedeep surface of the rotator cuff may be pinchedbetween these two structures and under repetitiveloading can lead to partial thickness tears of the


C

B

D

A

Figure 5-17. Passive tests for impingement are illustrated in A-D. A and B, Passive forward eleva-tion is used in which the greater tuberosity approximates the under surface of the acromion, oftenreferred to as the Neer test. The movement impinges on the suprahumeral tissues between the bonysurfaces. C and D, Another passive test for impingement abducts the humerus to 90 degrees and aforce is generated by the examiner’s right hand along the humerus. This position and force increasesthe compression load or impinges these tissues and directs increased loads to the acromioclavicularjoint. A patient with swelling in her suprahumeral tissues or at the AC joint will experience pain ascompression increases.

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tendon’s undersurface. Continuous compressive load-ing of the tuberosity on the labrum can also result inthe labrum loosening or becoming detached, thuscompounding the instability problem. We typically usea noninvasive test for internal impingement. We posi-tion the shoulder toward abduction and external rota-tion and then subtly use controlled and careful glidesof the humeral head while noting whether posteriorshoulder joint pain results with the position or gentletranslations.

Assessing Generalized ConnectiveTissue Laxity

Before we move the patient from the seated positionto the supine position, we conduct an assessment ofgeneralized ligamentous laxity. Body type influencesthe mobility of the joints because of the inherent elas-ticity of the connective tissues. The examiner needs tocheck quickly how much thumb hyperabduction,index finger metacarpophalangeal (MCP) joint hyper-extension, and elbow hyperextension is present to geta sense of the patient’s connective tissue makeup.When the examiner does this at this stage, he can con-duct the remaining mobility and stability tests with thepatient in the supine position with more accurateinterpretation.

Physiological Motion Testing

At this point, we move the patient to the supineposition (Table 5-11). Tests that have been performedfrom standing and sitting positions may be repeated inorder to confirm the patient’s previous responses tothe compressive, tensile, and shear stresses of theexamination. Confirmation of the patient’s responsesalso occurs with variations of the previously adminis-tered tests and additional tests that are best conductedfrom the supine position.

The passive physiological motion tests are the firstthat we typically perform from the supine position.We take the patient’s arm through passive flexion-extension, abduction-adduction, internal-externalrotation, and horizontal adduction. Note that a sig-nificant amount of shoulder joint motion in the car-dinal planes is from the contribution of thescapulothoracic articulation. Therefore when thepatient is lying supine with the scapula compressedagainst the table, the endrange of passive gleno-humeral motion is reached much earlier than whenthe scapula is free to move. Be sure to assess carefully

what is actually true glenohumeral motion, ratherthan total shoulder motion, with passive tests. Moreclinical skill is needed with assessment of true gleno-humeral motion from the supine position than typi-cally meets the eye.

Rather than limiting the assessment to the cardinalplanes only, the examiner needs to move the humerusin arcs of motion throughout the quadrant betweenthe sagittal and frontal planes, noting available range,where in the range pain is felt, and the end feel thatlimits the passive motion. Rotations are assessed fromvarying positions in the different quadrants. It isimportant to passively rotate the glenohumeral joint invarying degrees of abduction, scaption, and flexionin order to stress all parts of the glenohumeral jointcapsule and intrinsic ligaments.

Horizontal adduction is included in the passivephysiological tests for its assessment of the joint cap-sule and the effect of increased tensile stress to theposterior cuff muscles and a means to assess theendrange capabilities of the acromioclavicular jointand the ability of the tissues under the coracoacro-mial arch and over the coracoid process to toleratecompression.

The capsular pattern of the glenohumeral joint asdescribed by Cyriax is a passive pattern of motion thatreveals a marked limitation of glenohumeral externalrotation and an accompanying limitation of gleno-humeral abduction and internal rotation.4 The mosttypical “pattern” is one in which the external rotationlimitation is the most significant motion loss andglenohumeral abduction is the second most significantloss. The usual explanation for the pattern of motionloss is the loss of elasticity of the anterior pleats of theglenohumeral joint capsule (limiting external rotation)and a loss of the elasticity of the inferior pleats of thecapsule (limiting abduction).

Although this explanation helps us begin to under-stand the relationship of the anatomy of the joint cap-sule to movement, the syndrome adhesive capsulitis is


Table 5-11. Sequence of PhysicalExamination: Supine Position

Passive physiological motionsJoint play to glenohumeral jointStability tests (relocation tests)Apprehension testsJoint play to acromioclavicular and sternoclavicular joints

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much more complex because physiological changesare mostly at the cellular level (see Chapter 4).Typically the inflammatory process and tissue fibro-sis are centered in the subsynovial layer of the jointcapsule and the joint capsule may be adhered to thehumeral head itself.27 Tissue fibrosis also may occurin other regions of the joint capsule, leading to dif-fering patterns of movement. For example, a“reverse” capsular pattern for impingement prob-lems of the shoulder has been described in whichthere are more limitations in glenohumeral internalrotation than in glenohumeral abduction and exter-nal rotation.34 Additionally, it is important to realizethat patients with diabetes have a much higher inci-dence of shoulder joint capsule problems than thosewithout the disease.3,20,32 Therefore the pathogenesisof capsulitis is probably multifactorial and not simplya disuse phenomenon. We noted earlier that thereare three phases of “frozen shoulder,” or adhesivecapsulitis. Although a pattern may be present, it isperhaps more important to concentrate on the endfeel when passive tests are used in the physical exam-ination because it is the end feel, coupled with thepatient’s response to pain when the end feel isreached, that ultimately identifies the phase of thesyndrome present and directs the treatment process.

Joint Play and Stability Tests

We focus the next part of the examination on thequality of and the patient’s reponse to glenohumeraljoint play. Joint play refers to the accessory motions ofthe glenohumeral joint, as well as those incorporatedvia specific tests to determine the possible presence ofglenohumeral instability. Three of the more importantsigns that we look for include conditions in which thehumerus has less-than-normal movement with trans-latory motion of the humerus on the glenoid (capsulehypomobility), movements that either increase pain orresult in apprehension by the patient, or excessivemobility of the humerus on the glenoid with or with-out pain (capsule hypermobility). Be aware that ifthere is any muscle guarding or muscle spasm whilethe passive tests are performed, mobility of thehumerus on the glenoid cannot be accurately assessed.

Simple anterior, posterior, and inferior glides of thehead of the humerus on the glenoid with the patientin the side-lying position and the shoulder joint in the“loose packed” position (55 degrees abduction, 30degrees forward flexion, neutral rotation) are an excel-lent way to begin this portion of the examination(Figure 5-18, A and B).14 The examiner needs to applythe anterior and posterior forces in the scaption plane


BAFigure 5-18. Examination of anterior and posterior translations of the head of the humerus onthe glenoid with the patient in the supine position with the shoulder in the “loose-packed” position(55 degrees abduction, 30 degrees forward flexion, neutral rotation). We secure the head of thehumerus with one hand and grasp the distal humerus with the other hand. A simple anterior (A) andposterior (B) glide is used with the force being applied in the plane of the scapula (scaption plane)rather than the force being applied in the cardinal sagittal plane. Varying degrees of traction can beapplied to the humerus with the right hand.

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rather than the sagittal plane and determine thepatient’s response to the motion or the presence ofincreased or decreased mobility in comparison withthe opposite side. Although abnormal anterior laxityof the glenohumeral joint is the most common type ofinstability, posterior and multidirectional instabilitiesare increasingly recognized.

Numerous classification mechanisms for instabilitycan be used, including frequency and chronology, directionand degree of instability, etiology, and presence or absence of vol-untary control:

1. Acute, recurrent, or chronic conditions may bedescribed with regard to temporal background ofthe patient’s complaints.

2. Instability may occur anteriorly, posteriorly, or infe-riorly, or it may be multidirectional.

3. Articular surfaces may be completely separated(dislocation), or symptoms may result from abnor-mal translation without complete separation (sub-luxation).

4. Episodes of macrotrauma are common. Micro-trauma associated with repetitive use is very

common, especially in throwers, swimmers, andworkers with continual overhead demands.

Apprehension tests and relocation tests are often used toexamine the shoulder for instability. The simplestapprehension test is one in which the patient’s shoul-der is moved toward abduction and external rotation.Typically, the patient with a history of subluxations ordislocation has markedly increased muscle guarding orvoices fear (apprehension) of the shoulder “popping out”as external rotation is increased. We perform a reloca-tion test by placing one hand over the anterior shoulderof the supine patient (Figure 5-19, A-C ). A posteriorlydirected force is applied with the hand to prevent ante-rior translation of the head. Then the shoulder isabducted and externally rotated in the same mannerused with the anterior apprehension test. A positiveresult is obtained when this pressure used to stabilizethe head of the humerus and prevent it from sublux-ing anteriorly allows increased external rotation anddiminished associated pain and apprehension.

Finally, the joint play of the acromioclavicular andsternoclavicular joints can be assessed from the supine


B

C

A

Figure 5-19. In the relocation test: A, Theexaminer places his hand over the anteriorshoulder of the supine patient. B, A posteriorlydirected force is applied with the hand to pre-vent anterior translation of the head. C, Thenthe shoulder is abducted and externally rotatedin the same manner as in the anterior appre-hension test.

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position. Simple anterior-posterior pressures on thelateral aspect of the clavicle just adjacent to theacromioclavicular joint assess this joint’s tolerance toshear loads. The same anterior-posterior pressures atthe medial end of the clavicle just adjacent to the ster-num assess the sternoclavicular joint’s responses toshear.

Special Tests

Special tests including radiographic assessment,arthograms of the glenohumeral joint, magnetic reso-nance imaging of the shoulder, or diagnosticarthroscopy are important adjuncts to the patient his-tory and physical examination (Table 5-12). Neuraltension and thoracic outlet tests are controversial inboth their application and interpretation. The rele-vant anatomy for such tests and clinical considerationshave already been described in Chapter 2.

SUMMARY

We have provided a template from which to con-duct the patient history and physical examination forproblems related to the shoulder girdle as a basis forevaluation. Although there are numerous special testsavailable for the analysis of the shoulder, many areredundant. We encourage the reader to learn andunderstand the clinical anatomy and choose provoca-tional tests that make good clinical sense and can bereproduced from patient to patient. We have offeredan examination sequence that moves the patient infre-quently and allows the information gained to beapplied continuously to the next portion of the physi-cal examination. It is important to recognize that adiagnosis for shoulder problems is rarely made using asingular test but instead relies on correlating the

information gained from the history and results of thephysical examination.

In Chapter 6 we will look at specific problemsrelated to the shoulder and make suggestions regard-ing the organization of various interventions in orderto optimize treatment outcomes. The examinationdescribed here typically provides the information fromwhich a treatment plan can be developed and perhapsmore importantly results in gaining information,which allows the patient to assume responsibility forimportant aspects of the management process.

REFERENCES

1. Andrews JR, Gillogly S: Physical examination of the shoulder inthrowing athletes. In Zarins B, Andrews J, Carson W, editors:Injuries to the throwing arm, Philadelphia, 1985, WB Saunders.

2. Beaton D, Richards RR: Assessing the reliability and respon-siveness of five shoulder questionnaires, J Shoulder Hand Surg7:565, 1998.

3. Bridgman JF: Periarthritis of the shoulder and diabetes melli-tus, Ann Rheum Dis 31:69, 1972.

4. Cyriax J, Cyriax P: Diagnosis of soft tissue lesions. In Cyriax J:Textbook of orthopedic medicine, ed 6, Baltimore, 1970, Williamsand Wilkins.

5. Fung MF, Kato S, Barrance PJ, et al: Scapular and clavicularkinematics during humeral elevation: a study with cadavers,J Bone Elbow Surg 10:278, 2001.

6. Gerber C, Ganz G: Clinical assessment of instability of theshoulder, J Bone Joint Surg Br 66:551, 1984.

7. Hawkins RJ, Kennedy JC: Impingement syndrome in the ath-letic shoulder, Am J Sports Med 8(3):151, 1980.

8. Hawkins RJ, Mohtadi NG: Clinical evaluation of shoulderinstability, Clin J Sports Med 1:59, 1991.

9. Hazleman BL: Why is a frozen shoulder frozen? Br JRheumatology 29:130, 1990.

10. Heald SL, Riddle DL, Lamb RL: The shoulder pain and dis-ability index: the construct validity and responsiveness of aregion-specific disability measure, Phys Ther 77(10):1079,1997.

11. Howell SM, Galinat BJ, Renzi AJ, et al: Normal and abnormalbiomechanics of the glenohumeral joint in the horizontalplane, J Bone Joint Surg 70A:227, 1988.

12. Hulstyn MJ, Weiss AP: Adhesive capsulitis of the shoulder,Orthop Rev 22:425, 1993.

13. Jobe FW, Moynes DR: Delineation of diagnostic criteria andrehabilitation program for rotator cuff injuries, Am J SportsMed 10:336, 1982.

14. Kaltenborn FM: Mobilisation of the extremity joints: examination andbasic treatment techniques, Oslo, 1980, Olaf Bokhandel.

15. Kibler WB: Specificity and sensitivity of the anterior slide testin throwing athletes with superior glenoid labral tears,Arthroscopy 11:296, 1995.

16. Levine WN, Flatow EL: The pathophysiology of shoulderinstability, Am J Sports Med 28(6):910, 2000.

17. Maitland GD, Hengeveld E, Banks K: Maitland’s vertebral manip-ulation, ed 6, London, 2000, Butterworth-Heinemann.


Table 5-12. Special Tests forExamination of the Shoulder

Imaging studies of the shoulder complexArthrogramsAngiographyDiagnostic arthroscopyTests for thoracic outletUpper limb neural tension tests

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18. Matsen FA, Lippitt SB, Sidles JA, et al: Practical evaluation andmanagement of the shoulder, Philadelphia, 1994, WB Saunders.

19. Matsen FA, Thomas SC, Rockwood CA: Glenohumeral insta-bility. In Rockwood CA, Matsen FA, editors: The shoulder,Philadelphia, 1990, WB Saunders.

20. Moren-Hybbinette I, Moritz V, Shersten B: The clinical pictureof the painful diabetic shoulder—natural history, social con-sequences and analysis of concomitant hand syndrome, ActaMed Scand 221:73, 1987.

21. Mosely HF: Disorders of the shoulder, Clin Symp 12:1, 1960.22. Murnaghan JP: Adhesive capsulitis of the shoulder: current

concepts and treatment, Orthopedics 11:153, 1988.23. Neer CS II: Anterior acromioplasty for the chronic impinge-

ment syndrome in the shoulder: a preliminary report, J BoneJoint Surg Am 54A:41, 1972.

24. Neer CS II: Impingement lesions, Clin Orthop 173:70, 1983.25. Neer CS II: Shoulder reconstruction, Philadelphia, 1990, WB

Saunders.26. Neer CS II, Welsh RP: The shoulder in sports, Orthop Clin North

Am 8:583, 1977.27. Neviaser RJ, Neviaser TJ: The frozen shoulder: diagnosis and

management, Clin Orthop 223:59, 1987.

28. O’Brien SJ, Pagnani MJ, Fealy S, et al: The active compressiontest: a new and effective testfor diagnosing labral tears andacromioclavicular joint abnormality, Am J Sports Med 26:610,1998.

29. Perry J: Anatomy and biomechanics of the shoulder in throw-ing, swimming, gymnastics, and tennis, Clin Sports Med2(2):247, 1983.

30. Porterfield JA, DeRosa C: Mechanical low back pain: perspectives infunctional anatomy, Philadelphia, 1998, WB Saunders.

31. Roach KE, Buhiman-Mak E, Songsiridej N, et al: Developmentof a shoulder pain and disability index, Arthritis Care Res4(4):143, 1991.

32. Sherry DD, Rothstein RRL, Petty RE: Joint contractures pre-ceding insulin-dependent diabetes mellitus, Arthritis Rheum25:1362, 1982.

33. Snyder SJ, Karzel RP, Del Pizzo W, et al: SLAP lesions of theshoulder, Arthroscopy 6:274, 1990.

34. Wilk KE, Arrigo CA: Current concepts in the rehabilitation ofthe athletic shoulder, J Orthop Sports Phys Ther 18:365, 1993.


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INTRODUCTION

In this text we have emphasized that a detailedunderstanding of the anatomy, especially the relation-ships of individual tissues and structures to one other,is requisite to effective application and interpretationof various aspects of the physical examination and toimplementation of appropriate treatment interven-tions. References to video clips have been placed atkey points throughout Chapters 2, 3, and 4 to enhancethis understanding, highlight its clinical relevance, andprovide the reader with a three-dimensional apprecia-tion of the pertinent anatomy. On gaining a thoroughunderstanding of the region, it becomes easier to visu-alize the mechanisms by which different structuresrelated to the shoulder girdle are stretched and com-pressed and move in relation to one another duringexercise or as a result of the application of any man-ual techniques. We encourage the reader to use theaccompanying anatomical DVD often during this dis-cussion of rehabilitation for the shoulder, especiallywhen considering exercises. Visualizing the anatomyin this way will augment the reader’s ability to scien-tifically analyze the potential effects of every aspect oftreatment and allow appropriate modification of exer-cises or movement patterns based on examinationfindings.

The basic tissues of primary concern in the treat-ment of mechanical disorders of the shoulder are theconnective, muscle, and nerve tissues. Examples of themost commonly seen medical diagnoses of the shoul-der, with reference to the tissues of primary concern,include:

● Shoulder instability (connective tissues)● Rotator cuff tears and surgical repairs (muscle and

connective tissues)● Calcific tendonitis (connective tissues)● Complex regional pain syndrome (nerve tissue)● Repetitive strain syndrome (muscle tissue)● Glenoid labral lesions (connective tissues)● Neurovascular compression syndromes (nerve tissue)● Acromioclavicular joint disorders (connective tissues)● Fractures and total joint arthroplasty (connective

tissues)

When working from this tissue construct, the princi-ples of treatment are very similar to those for theextremities and the spine. In this chapter we will suggestthat by coupling the four objectives of treatment (patienteducation, pain modulation, movement promotionthrough strategically applied forces, and neuromuscularefficiency enhancement) with an understanding of theresponse of tissues to aging and injury, a logical andeffective plan of care can be established.

CHAPTER 6TREATMENT OFMECHANICALSHOULDER DISORDERS

161

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Disorders of the shoulder are a particular challengebecause of the inherent instability of the various artic-ulations and the limited understanding of the complexyet highly coordinated roles the neuromuscular systemplays over these same articulations. The enormouslywide range of surgical and nonsurgical interventions(for example, thermal capsular shrinkage, exercise,acromial resection, rotator cuff repair, capsular shifts,bone and tendon translocations, subacromial debride-ment, rest, prolotherapy) not only reinforces thatscience has a surprisingly limited understanding of theshoulder complex but also suggests that no oneformula exists for shoulder treatment.

Trying to determine the best treatment for shoulderdisorders is extremely difficult owing to the realities ofclinical practice. Since it is problematic to select ahomogenous group of patients with precisely the sameanatomical lesion responsible for the shoulder disor-der, it is very difficult for outcome studies to compareand contrast the results of treatment interventionsbetween patient populations. Diagnostic labels mustbe valid and reliable if treatment results are to becompared. Yet it is not simply the difficulty in estab-lishing a meaningful diagnostic label that rendersanalysis of a homogenous group of patients withmechanical shoulder disorders difficult but also suchfactors as the patient’s work requirements, social roles,myriad insurance and legal influences, and the uniqueand individualized responses that each individual hasto pain stimuli and disability.

Despite such limitations, treatment can be based onthe known sciences related to tissue aging, injury, heal-ing, and repair. In addition, the effect of exercise onthe promotion of general health, physical well-being,and enhancement of tissue strength and function iswell accepted and understood. It is on these strongfoundational principles that this chapter is based.

GENERAL CONCEPTS

For the most part musculoskeletal tissues heal pre-dictably. This is an important point to recognize inplanning the treatment process for mechanical disor-ders of the shoulder. The literature is replete withinformation regarding the healing potential ofbone,4,5 tendon,16,19,25 ligament,2,8 muscle,14

nerve,3,20 and cartilage.6,17,18 Therefore rehabilitationfor any musculoskeletal disorder should by definitionfollow foundational guidelines that have been estab-lished for these tissues.

The uniqueness of any rehabilitation program,however, becomes dependent on the functionaldemands of that region. Therefore while the founda-tional rehabilitation principles regarding tissue repairmight be similar for rehabilitation of the shoulder, lowback, or knee, the uniqueness of the rehabilitation pre-scriptions is dependent on the functional demandsthat the region is currently being subjected to and isexpected to be subjected to in the future.

This is the primary reason that the concept of forceattenuation was introduced in Chapter 1 and thencontinuously reiterated in subsequent chapters, cul-minating in Chapter 5, with this paradigm being theessential focus of the examination process. The rela-tionship of the loading response from functionaldemands to treatment of mechanical shoulder disor-ders is extremely important. Management strategieswill need to be tailored to and implemented for con-ditions as varied as those seen in the throwing athlete,the older adult patient with full thickness tear of therotator cuff, the swimmer, the overhead worker, thegymnast, the tennis player, the patient with neurovas-cular compromise to a component of the brachialplexus, or an individual who insidiously loses gleno-humeral capsular resiliency within a few days.

Accurate mechanical diagnosis and the implemen-tation of appropriate interventions are thus inti-mately related. Being able to predict the outcome ofthe treatment dosage based on the interpretation ofthe findings of the history and physical examination,along with meaningful and practical patient educa-tion, is closely related to quality patient care. In theshoulder, particularly with the dominant side, the keyto any treatment approach is to minimize, and in thebest of circumstances, prevent the overload to theinjured tissue while staying active. The assessmentprocess suggested in Chapter 5 helps the cliniciandetermine the “barrier,” the position of the extremityor the loading response of the tissues that just beginsto stimulate the nociceptive system or reproducessigns or symptoms similar to the original problem forwhich the patient has sought help. Once such a bar-rier is determined, the clinician must decide whetherrehabilitation should work through that barrier,mechanically stressing the repairing tissues, or bedesigned to work away from the barrier, recognizingthat the force attenuation capabilities of the tissueshave been irrevocably lost. Such a decision becomespart of the guiding philosophy behind designing theplan of care and is scientifically grounded when theloading responses of tissues, the effects of age and

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injury on tissues, and recognition of the three majorinfluences on the painful response (chemoreceptoractivation of the nociceptive system, mechanorecep-tor activation of the nociceptive system, and the influ-ence of psychosocial factors on the pain response) areunderstood.

In order for any rehabilitation program to be effec-tive, the patient must also take “ownership” of hisproblem. It is therefore important for the patient to seeand understand the similarities of the positions andforces mentioned above in his activities of daily livingor the requirements of his work or sport. In order forcollagenous structures to repair, a balance between tis-sue loading and controlled rest must be struck. Thisbecomes one of the primary dilemmas with rehabilita-tion of the shoulder, especially in regard to work andsport requirements. The successful clinician helps thepatient analyze movement and the relationship ofmovement to healing and potential reinjury. Thepatient must then pay particular attention to thoseactivities that are more reflexive or subconscious innature, such as arising from his chair, opening and clos-ing heavy glass doors, reaching overhead for cups anddinner plates, lying on his shoulder when falling asleep,or abruptly lifting heavy objects, among a wide array ofmovements, and be able to relate these to his shoulderimpairment or functional loss. The successful patientwill make the temporary changes in physical behaviorthat minimize the overload, while remaining active. Atthe risk of being redundant, it is important to remem-ber that this is the primarily purpose of the evaluationsystem as outlined in Chapter 5: to provide the clini-cian and the patient with a knowledge base that allowsfor the implementation of practical solutions to bal-ance activity and rest.

We have already seen that the neurology of theupper quarter is complex and intricate. Also, it mustalways be considered in the design of treatment pro-grams. In many ways, the upper quarter neurology ismore complex than that of the lower extremitiesbecause of the density of sensory receptors and mus-cle spindles present here. Unlike other areas of thebody, pain anywhere in the upper quarter has thepotential to exacerbate symptoms within the entireregion. Several examples illustrate this:

● The source of pain may be in the neck, but thepatient also complains of his entire arm aching, aswell as ringing in the ears.

● The patient with a degenerative segment in his cer-vical spine feels pain “right between my shoulder

blades” when he extends his neck and laterallyflexes toward one side.

● The patient complains of pain along the back ofthe arm, scapular regions, and neck after injuringhimself while performing a pull-up.

● The patient with the frequently dislocated shouldercomplains of headaches and pain at the superiormedial border of the scapula.

● The patient with a trivial injury to the wrist andhand develops edema, pain, and discoloration ofthe complete arm and forearm and is unable to tol-erate any sensory stimulus to the upper quarter.

● The patient presents with carpal tunnel syndromebut on close examination also has shoulder pain andevidence of cervical nerve root involvement.

● The patient attempts a new exercise on a selector-ized exercise machine at his local exercise facilityand feels an immediate discomfort in the shoulder,which then results in neck stiffness and diffuse armpain the following day.

These examples demonstrate that it is not only theanatomical linkages of tissues that have beendescribed in this text that are important to recognizebut also the neurology of the region. Both must betaken into consideration when examining any patientwith upper quarter pain.

Finally, we must mention the importance of move-ment in the early phases of rehabilitation. With mostinjuries, the sooner the injured region can be movedinto and through a painful range of motion with anintensity, frequency, and duration that does not exac-erbate the condition, the more rapid the recovery.Moving through the painful range at the appropriaterate and amplitude requires guidance by the clinicianand is an essential factor in facilitating functional heal-ing and ultimately the determination of future func-tional limitations.

INTENT OF TREATMENT

The intent of treatment has four basic compo-nents:26

1. Optimize the healing environment.2. Restore anatomical relationships between the

injured and noninjured tissues.3. Maintain the normal function of the noninjured

tissues.4. Prevent excessive stress or strain to the injured

tissues.

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Optimize the Healing Environment

Healing of collagenous structures can be describedin three phases: reaction, regeneration, and remodel-ing.26 The reaction phase calls on specific cells to cre-ate the cellular and chemical environment required fortissue repair. Mast cells, granulocytes, leukocytes,fibroblasts, and myofibroblasts respond and reach theinjured and surrounding regions quickly. This barrageof cells, when coupled with the inflammatory exudatethat results, creates a “biological soup.”28 This is anexcellent analogy because it provides a strong visualimage of the thickened fluid–like nature of the envi-ronment and the tissue stasis that result. This soupbecomes the basis for increased tissue pressure, whichretards lymph drainage and microcirculation, render-ing the area hypoxic and acidic. The depolarizationthreshold of the nociceptive free nerve endings lessensas the pH decreases, resulting in axonal depolarizationand increased afferent input into the central nervoussystem. The resultant pain can begin a cascade ofevents, including muscle spasm, decreased blood flow,and increased fluid congestion.

The goal with treatment is to maximize the healingenvironment through restoration of the microcircula-tion environment and is often best accomplishedthrough graded and controlled movement. This is bestintroduced by the clinician in the form of passive,active assistive manual techniques, active movements,or controlled muscle contractions over the area.

Time frames need to be considered with this treat-ment intent and are dependent on the circulation pres-ent in the region and the age of the patient. In anadolescent a well-vascularized area may require as lit-tle as 6 to 8 weeks for reasonable repair of connectivetissues, whereas a young adult may require 8 to 12weeks. At the other end of the spectrum, the olderadult patient with an injury in an area with less optimalvascularization, such as the rotator cuff tendons, mayrequire 6 to 9 months for reasonable repair, if repair iseven possible. In all cases, repair of collagenous tissuesultimately results in some loss of function.10,22,29

Restore Anatomical RelationshipsBetween the Injured and NoninjuredTissues

This second intent of treatment refers to the intro-duction of movement designed to stress the injuredtissues in a way that stimulates functional healing and

allows the tissues to begin assuming their role of loadattenuation in concert with the surrounding tissues.Restoration of the strength, length, and motion capa-bilities of the injured tissue relative to the surround-ing region is important if loads are to be effectivelydistributed via multiple tissues in the region. Tissuesmust be able to glide over, compress onto, and exerttension to the attached tissues. This ultimately resultsin functional healing.

Maintain the Normal Functionof the Noninjured Tissues

The third intent of treatment is designed to intro-duce the right dosage of movement and tissue loadingin order to simultaneously maintain tissue health andreduce disuse atrophy. The dosage is important, andclinicians always must keep in mind that symptomreduction in and of itself is not the best indicator oftissue repair. For example, the degenerated andpainful rotator cuff may become asymptomatic, but itsability to tolerate loads may not have appreciablychanged. Excessive load to the degenerated asympto-matic rotator cuff tendon can result in a partial thick-ness tear increasing to a full thickness tear. A fine linealways exists between too much and too little activity.A direct relationship exists between the restoration ofmicrocirculation, the required healing times forinjured or surgically repaired tissues, and the intro-duction of movement for healing.

Prevent Excessive Stress or Strainon the Injured Tissues

The final intent of treatment requires an under-standing of the mechanics of the articulations related tothe shoulder girdle and the requirements of muscleactivity during functional activities. Clinicians candesign exercise programs or apply manual techniquessafely and without compromise to the injured regiononly when those interventions are based on a completeunderstanding of the anatomy and biomechanics of theregion. For example, when any exercise is being per-formed, the clinician should be able to clearly visualize:

● When the acromioclavicular joint is placed at itsendrange

● When the supraspinatus tendon is simultaneouslyloaded in compression and tension


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● What position of the glenohumeral joint places thegreatest tension to the anterior-inferior gleno-humeral ligament

● What motions of the upper extremity place thegreatest stress to the long head of the biceps tendon

● What position of the shoulder puts the greateststress to a subacromial region that has recently beensurgically debrided

● What exercises place the greatest degree of fric-tional loading on a recently repaired anterior gle-noid labrum

● What sleeping postures stress an inflamed and irri-tated glenohumeral joint capsule

These types of joint and tissue specific analyses con-tinually guide the clinician’s treatment approach, espe-cially regarding development of the exerciseprescription. While it is important to guide the patientthrough a painful range of motion without further exac-erbation of symptoms, it cannot be done at the expenseof placing excessive stress on the injured tissues.

PRIMARY INFLUENCES ON THEPAIN RESPONSE

When considering the wide range of clinical pre-sentations possible in patients with shoulder girdle dis-orders, two theoretical questions should be consideredin order to better appreciate the complexity of thepain response:

1. Can pain exist without inflammation?2. Can inflammation exist without pain?

Theoretically, both scenarios have the potential toexist. Pain without inflammation might best be inter-preted as mechanical pain, that is, stimulation of themechanoreceptor nerve endings when endranges ofmotion result in tissue distortion great enough to resultin depolarization of the afferent nerve endings with-out tissue damage. When the excessive force or motionis removed, the discomfort decreases or is diminished.

It is reasonable to assume that the answer to thesecond question is also “yes” because, again, wemust take into account the depolarization thresholdof the nociceptive system, this time chemicallyinstead of mechanically. High depolarization thresh-old refers to the necessity of a larger stimulus beingrequired for axonal discharge, while a low thresholdrequires less or little stimulus for axonal depolariza-tion. The threshold is reached because of sufficient

chemical activation of the nociceptive system. Inmany patients with shoulder disorders, one oftenhears of a “pre-pain continuum” during the history,which begins with stiffness and movement com-plaints, after which an appreciation of pain occursat a later time.

Pain is also influenced by emotions and the individ-ual’s behavioral responses to his surrounding environ-ment. Factors such as family stress and job stress andemotional states including fear and depression all con-tribute to the complexity and uniqueness of the per-ception of pain, the pain response, and the ultimateresponse to treatment. Therefore in planning thetreatment of mechanical disorders of the muscu-loskeletal system, the clinician should first considerthese three influences on pain:

● Chemoreceptor or biochemical cycle● Mechanoreceptor cycle● Emotional or behavioral cycle

The clinician also needs to be cognizant of the var-ious behavioral and physiological responses that occuras a result of these three stimuli. Figure 6-1 illustratesthis via the use of a clockwise spin of three cycles:chemoreceptor, mechanoreceptor, and emotional/behavioral. Each cycle includes the associated physio-logical or behavioral changes that occur. Pain percep-tion is typically due to a contribution from each cycle,and during the assessment and reassessment processes,the clinician is always attempting to ascertain whichthree cycles are “spinning” to the greatest degree. Inother words, what is the primary stimulus contributingto the disorder?

Determining which of the three cycles predomi-nates ultimately influences what interventions willbe applied. For example, pain syndromes that arethought to be primarily influenced via the chemore-ceptor cycle are best treated with carefully con-trolled motion and appropriate rest. Workingthrough the barrier would most likely exacerbate thecondition, as might the initiation of resistance exer-cises. Pain that is primarily caused by themechanoreceptor cycle has less inflammation andtissue damage associated with the disorder and cantolerate more loading to the tissues. Thus it can betreated with more active approaches such as incor-porating resistance exercises and more aggressivejoint mobilization and stretching activities. Suchconditions can often be treated into and through thebarrier. When the emotional/behavioral cycle isthe major influence, patient education becomes the


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primary treatment approach. Less hands-on inter-vention is used because the pain generator has min-imal mechanical or chemical basis. While all threecycles contribute to the painful syndrome, the clini-cian is attempting to determine the hierarchy ofeach cycle’s influence and then use the appropriatetreatment techniques indicated to match each cyclewith such a hierarchy.

OBJECTIVES OF TREATMENT

While there are anatomical differences andunique functional demands for each region of themusculoskeletal system, four basic objectives oftreatment for orthopedic mechanical disorders existthat should be considered regardless of the region.These objectives are:


Gradualwithdrawal Decreased

motivation

Decreasedself-esteem

Decreasedsocial/professional

interactionEMOTIONAL/BEHAVIORAL

MALAISEDecreasedconfidence

Increased mechanicalstresses to injury

Early onsetfatigue

Decreasedmuscle action

(protectiveguarding)

Decreased fluidcongestion

Protectiveguarding

Decreasedblood flow

Biochemicalimbalance (pH)

Decreased Activity

INJURY/DEGENERATION

PAIN

SPASM

MECHANORECEPTORSCHEMORECEPTORS

Figure 6-1. The injury-degenerative cycle illustrates the factors affecting the perception of pain.These stimuli can be viewed as three separate “spinning cycles.” They include the chemoreceptor,mechanoreceptor, and emotional-behavioral cycles. Pain can be related to each individual cycle or toa combination of the three. Chemoreceptor cycle: The nociceptive effects of fluid stasis and altered bio-chemistry of the injured region, often noted as morning stiffness by the patient. Mechanoreceptor cycle:The effects of early onset fatigue and decreased activity, often noted as pain at the end of the day bythe patient. Emotional-behavioral cycle: Shows the influence of psychosocial stressors on the patient.When viewing these three components as spinning cycles, the clinician attempts to determine whichof the cycles is dominant or the most responsible for the pain perception and therefore should takeprecedence in establishing the treatment process. (From Porterfield JA, DeRosa C: Mechanical low backpain: perspectives in functional anatomy, ed 2, Philadelphia, 1998, WB Saunders.)

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1. Patient education and biomechanical counseling2. Modulation of pain and the promotion of analge-

sia3. Application of controlled forces to promote patient

activity4. Enhancement of neuromuscular health and per-

formance

We will consider each of these objectives in relationto the development and implementation of treatmentinterventions for painful disorders of the shouldercomplex.

Patient Education andBiomechanical Counseling

Appropriately directing the responsibility of recov-ery to the patient via education is the key to any suc-cessful rehabilitation program. It is important to realizethat if a patient is treated in a clinical environment 3days a week for 1 hour at each visit, the clinician isinteracting with the patient only for a very small per-centage of the time that the patient is awake andactive. What the patient is doing away from the clinicalenvironment becomes critical to care management. Inorder to obtain the best results from a rehabilitationprogram, the patient must understand his injury andwhat his own contribution must be to the rehabilitationprocess. Establishing reachable, realistic, short- andlong-term goals becomes a very important aspect ofthis process since it underscores the significance of thepatient’s involvement in the treatment process.

Patient education needs to include an explanationof anatomical and biomechanical aspects of the injuryor condition, the rationale for the suggested treatmentprogram, and the expected outcomes. One veryimportant aspect of the initial stages of the treatmentprocess is to assist the patient in understanding therelationships between the intervention and theexpected outcome. In most cases, the initial outcomeis a decrease in pain and an increase in function, afterwhich there are more complex outcomes such as thedevelopment of specific neuromotoric skills that canbe set as goals. The latter are especially important indealing with the painful shoulder of the patientreturning to sport or industry.

When treating the patient with an acute injury, theoptimal reassessment of the patient has to take placewithin the most immediate time period followingtreatment. Often the constraints of authorized visits

and insurance limitations influence this, but optimalcare is achieved when the results of treatment for theacute injury are promptly assessed. A daily reassess-ment, for example, permits the clinician to substanti-ate his findings and understanding of the extent ofthe injury. Following an initial treatment, the clini-cian might predict such changes as the extent of painrelief that the patient should experience, a change inthe referral zone of pain, how easy or difficult it willbe for the patient to sleep that night as a result oftreatment, and the amount of stiffness that thepatient might experience the following morningupon awakening. When the patient returns to theclinic on a subsequent visit, the predictions are revis-ited by both clinician and patient and revised deci-sions regarding further interventions are made.Outcome prediction following the subsequent treat-ment is repeated again, with the result being that theclinician ultimately can confidently predict the extentof the injury and the short- and long-term course ofthe rehabilitation program. If the clinician hasgained the essential information from the patient his-tory, clearly understands the ease in which painfulresponses can be elicited, and knows how the shoul-der girdle will be used in work and activities of dailyliving, such predictions often can be made with ahigh degree of accuracy.

Biomechanical counseling establishes those posi-tions, movements, and forces that have the potential tocompromise the patient’s shoulder injury in activitiesof daily living, work, and sport throughout each phaseof the recovery process. Making correct judgmentsand providing clear explanation about the demandsof various activities of daily living on his injury is animportant clinical skill. Decisions regarding thepatient’s gradual progression of activity during reha-bilitation and the demands associated with return towork or reactivation into sport must be based onobservation, accurate prediction, and effective plan-ning. The shoulder complex is involved in almost allactivities of daily living and sport, and therefore keep-ing the loads under the injury threshold throughoutrehabilitation is important.

In most mechanical shoulder disorders, it is unusualto progress completely through the rehabilitationprocess without some form of exacerbation of thecondition. It could be successfully argued that a mildincrease in symptoms along the rehabilitation contin-uum is helpful in determining the upper limit of tissuetolerance as the patient progresses from one stage ofactivity to the next. The dialogue established between


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patient and clinician is one of the main factors in thesuccessful return to painless activity.

There are numerous examples of patient educationand biomechanical counseling that are used to helpthe patient manage his shoulder disorder. Many canbe surmised from the mechanics of injury discussed inChapters 2, 3, and 4, and additional examples areincluded in the case studies in the final section of thischapter. Several practical examples to share withpatients are listed here in order to relate this objectiveof treatment to selected shoulder impairments andfunctional limitations:

● Avoid carrying heavy purses or backpacks over oneshoulder when symptoms of brachial plexusinvolvement or neural entrapment are present.

● Avoid excessive scapular retraction in the presenceof symptomatic degenerative joint disease of theacromioclavicular joint.

● Modify rowing exercises in the presence of longhead of the biceps tenosynovitis.

● Avoid any shoulder elevation exercises that leave theglenohumeral joint in a relatively internally rotatedposition.

● Realize the importance of trunk rotation (whenthrowing) during the acceleration and decelerationphases.

● Make sure enough body roll is occurring during therecovery phase of swimming in order to avoidabnormal glenohumeral joint motion.

● Realize increased thoracic extension and scapularretraction occur when carrying out tasks in theoverhead position for extended periods of time.

These examples use the biomechanical knowledgeof shoulder girdle function to provide specific andindividualized advice to a patient regarding protectionof his injury.

Modulation of Pain and thePromotion of Analgesia

Shoulder pain often is poorly tolerated. Pain toler-ance is lessened by the inability to assume a comfort-able position for sleep, the inability to move theshoulder in activities of daily living without provokingpain, or the presence of sharp episodes of pain onsimple shoulder movements. Because pain is also apart of the healing process, it serves as a warning sig-nal that assists us in making the correct decisionsregarding motions and tissue loading patterns.

Pain modulation interventions are important inorder to begin to reintroduce functional activities at theearliest possible opportunity. Several different strategiesare available that meet this objective of treatment.Controlling exuberant inflammation and hence pain isthe primary reason for using medication as a strategyto meet this objective. This includes nonsteroidal anti-inflammatory drugs (NSAIDs), steroidal medications,and corticosteroid injections. In several disorders ofthe shoulder, the rapid control of inflammationbrought about by corticosteroid injections is the bestmanagement strategy, as in the case of the rapidonset subacromial bursitis. Although such a problemmight also be treated with ice and antiinflammatorymedication, an injection of corticosteroid and anal-gesic into the region provides rapid relief and moreimportantly does not allow the glenohumeral jointto remain immobilized as a result of pain for anextended period of time. Analgesics used alone inthe treatment of mechanical shoulder disorders areprimarily used for pain modulation without antiin-flammatory qualities.

The most difficult question here is determiningthe length of time to use such a medication and howto couple its use with the active rehabilitationprocess. Monitoring the changing level of pain rep-resents one of the best guides in directing the pro-gression toward recovery. Oftentimes medication isused until the patient can comfortably sleep throughthe night.

Avoid muscle relaxants during the active rehabilita-tion process. They are primarily used to enhance thepatient’s ability to sleep and often may make thepatient groggy. The appropriate resting state of mus-cle activity helps to control the loads that need to beattenuated for injured tissues during even the simplestof movements and postures. Therefore, depending onthe problem, decreasing muscle activity is not alwaysin the patient’s best interest.

Proper hydration is essential while taking medica-tions. Fatigue, one of the more common indicators ofdehydration, is most often seen as a side effect whenpatients are taking medication and needs to be moni-tored by the clinician.

Thermal and electrical modalities administered tothe injured region of the shoulder in the most com-fortable position can often be coupled with manualtechniques to stimulate fluid dynamics and helpdecrease pain as a result of alteration of the chemicalenvironment associated with the injured tissue. Iceapplied to the shoulder in the form of ice massage,


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coupled with soft tissue and joint mobilization tech-niques, also produces advantageous results.

Application of Controlled Forcesto Promote Patient Activity

The objective of applying controlled forces refers tothe clinician’s ability to introduce motions in such away that active movements by the patient are subse-quently encouraged. There are numerous ways inwhich controlled forces can be effectively used in themanagement of mechanical disorders of the shoulder.Table 6-1 lists active, manual, and mechanical treat-ment techniques that are often used in this objective oftreatment. Although many different explanations havebeen made regarding the effects of these techniques,we believe that the physiological outcomes of all ofthe techniques are remarkably similar and can bedistilled to a combination of the following:

● Stimulation of fluid dynamics. As previously mentioned,stasis results in an altered biochemical environmentassociated with the region of injury and this chemicalenvironment activates the nociceptive system. Activemotion and some of the passive motion techniqueshelp move tissue fluid along a gradient, thus alteringthe chemical milieu associated with injured tissue.

● Increasing afferent input into the central nervous system.Many of the manual and active techniques providemechanoreceptor input into the central nervous sys-tem, which has a twofold reflexive effect.

● Enhanced modulation of pain. Many of the joint andsoft tissue techniques have sufficient mechanorecep-tor stimulation to help modulate the afferent painimpulse emanating from the injured region at thecentral nervous system level; this is especially

important when dealing with the exquisitely painfulglenohumeral joint capsule.

● Modulation of the resting state of muscle contraction. Manyof these techniques are effective in decreasing mus-cle spasm and guarding through the reflex connec-tions associated with mechanoreceptor input.

● Modification of connective tissue. This is especiallyimportant when considering rehabilitation follow-ing surgery; recently injured or surgically repairedconnective tissues respond to applied forces by stim-ulation of new fibroblast formation and realign-ment of collagen fibril orientation.

The total endrange time or time that the joint isheld at the end of its available range becomes animportant consideration because it is this parameterthat has the most significant effect on the modulationof connective tissue length.7,15

Soft tissue techniques (Figure 6-2) and joint mobi-lization techniques (Figure 6-3) are often used to man-age pain and inflammation and can be obstacles toactive movement. As noted in Chapter 4, variousaccessory joint mobilizations are designed to improvegeneral joint mobility. Do not think of them asincreasing one particular physiological motion overanother. The longer the time frame of the injury, how-ever, or the more the healing scar proliferates, thegreater the cross linking of the collagen fibrils. Thus atsome point there is a reduced ability to actually mod-ify connective tissues through any mobilization orstretching techniques.

Oftentimes manual treatment of the upper quarterhas physiological effects on the surrounding area aswell, most likely because of the increased afferentinput afforded by the stimulation of the joint, muscle,tendon, and skin mechanoreceptors. Therefore treat-ment often is directed to the primary region of


Table 6-1. Application of Controlled Forces to Promote Patient Activity

Passive Manual Techniques Mechanical Interventions Active TechniquesGlenohumeral joint mobilization Shoulder slings Active range of motionScapulothoracic mobilization Shoulder taping Muscle energy techniquesAcromioclavicular and sternoclavicular Shoulder abduction splints Proprioceptive neuromuscular facilitation

joint mobilization Isometric stabilizationSoft tissue mobilizationPhysiological joint and muscle stretchingCross friction massageEffleurageAcupressure

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Figure 6-2. A-D, Although soft tissue techniques can be used over any area of the shoulder girdle,the tissue techniques are primarily used over the scapulothoracic articulation. In these examples thescapula is passively moved by the examiner along all available planes of motion. E, The sequencemoves clockwise. (From Porterfield JA, DeRosa C: Mechanical neck pain: perspectives in functional anatomy,Philadelphia, 1995, WB Saunders.)

C

B

D

E

A

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involvement, as well as associated regions. For exam-ple, internal derangement within the glenohumeraljoint, such as seen in a torn glenoid labrum, may initi-ate protective guarding (spasm) and pain throughoutthe upper quarter. This, in turn, results in cervicalspine discomfort, scapulothoracic complaints, andheadaches, perhaps as the result of abnormal andexcessive spine and scapula muscle activity.

Finally, splints and taping of the various shoulderarticulations often are used in an attempt to controlhow forces reach the region and therefore such inter-ventions also fall under this objective of treatment.Abduction splints are especially important in somesurgical repairs because the positioning of the armwith such splints minimizes the chances that adhesivecapsulitis will develop. Taping of the anterior aspect ofthe glenohumeral joint in the case of chronic anteriorsubluxation is another such intervention.

The following examples illustrate how this objectiveof treatment is used in selected shoulder disorders:

● Passive stretching to increase glenohumeral externalrotation in order to allow the patient to avoid sub-acromial compression when raising the arm over-head

● Small and controlled translations of the humeralhead on the glenoid using very specific handholds to

treat the patient with a humeral shaft fracture inorder to help maintain some degree of capsularmobility and avoid secondary adhesive capsulitis

● Use of a sling to support the upper extremity inorder to counter the gravitation pull to the scapulaon the clavicle in the recently injured acromioclav-icular joint

● Cross friction to the infraspinatus tendon to helpmobilize the connective tissue and also induce ahyperemic response in the mildly involved case ofinfraspinatus tendonitis

● Glenohumeral joint mobilization using an inferiorglide translation “stretch” to help decompress thesubacromial space and allow for active overheadmovement to be initiated

● Use of rhythmic internal and external rotation oscil-lations in order to treat the acutely painful capsulitis

● Manual stretching of the pectoralis major andminor to decrease the shoulder protraction positionand minimize subacromial compression

● Use of a shoulder wand or L bar to introduce activeassistive motion in the shoulder that has beenrecently surgically repaired

● Codman’s exercises to apply passive range-of-motion techniques to the glenohumeral joint, whichallows gravity to decompress the loading betweenthe humeral head and the glenoid


BAFigure 6-3. General mobility of the glenohumeral joint can be encouraged with the use of passivephysiological motion in conjunction with various translations of the humeral head on the glenoid.Shown in this example are anterior, A, and posterior glides, B, of the humerus on the glenoid, use-ful as a supplemental technique to help restore or improve general joint mobility. During these acces-sory motion techniques, one must be cognizant of the joint plane and then be certain that movementof the two bones relative to one another remains parallel to this joint plane.

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Enhancement of NeuromuscularHealth and Performance

The rehabilitation process shifts toward resistedexercise once motion has been restored, the patient issleeping through the night and waking up withoutexcessive stiffness or soreness (one of the best indica-tors of an inflammatory condition), the time of painrelief from treatment is lengthening, and the inten-sity of pain has been lessened. Injuries to the con-nective tissues associated with the articulations of theshoulder girdle result in a loss of stability. Becauseconnective tissues repair rather than regenerate,restoration of stability will not come from the con-nective tissue contribution but instead fromenhanced neuromuscular control. Therefore thisobjective is very important.

Several definitions are important to understand. Anoperating definition of strength indicates that therecruitment of motor units allows the muscle to gen-erate sufficient tension to overcome a given load orresistance. Power refers to the amount of force that canbe generated over a unit of time, whereas endurance isthe ability of the neuromuscular system to sustain agiven force or repeated contractions. Coordination, themost complex of motor functions, is the integration ofcortical, subcortical, and spinal cord levels of controlwith the receptor system associated with the joints andsoft tissues. Coordination also includes the motorplanning that actually precedes the activity. Exerciseprograms designed around the enhancement of neu-romuscular health and performance need to includethese parameters.

Use of poor exercise technique can result in furtherinjury, oftentimes compounding the original injury. Itis very important then that the clinician is able toassess the biomechanics of each exercise, especially asresistance or repetitions are increased, and successfullymatch these mechanics to the positions and move-ments that have been altered as a result of the injuryor degeneration. The successful clinician visualizes theanatomy of the shoulder girdle, spine, and trunk inthree dimensions during movement and then assessesthe structural and load-bearing changes imparted tothe joint structures and related tissues. This knowledgepermits the clinician to customize the strengtheningprogram to meet the needs of each patient. The goalis to develop resisted movement patterns that appro-priately load each tissue within the shoulder complexwithout injury. Such treatments are based on thefollowing concepts:

● Movement enhances healing.● Movement against resistance can enhance connec-

tive tissue strength and muscle strength.● Greater overload applied causes greater tension

generating demands of the muscle and thus thepotential for muscle hypertrophy.

● Resistance coupled with repetition leads to neuro-motoric changes and motor learning.

The challenge is to effectively teach the patient howto exercise against resistance using proper biomechan-ics until a change in the quality of the motion occursand proper form is lost. The patient must develop theability to move the humerus irrespective of the scapula,scapula irrespective of the humerus, and both in con-cert with the trunk. Fatigue of any one aspect of theshoulder girdle mechanism can result in movementsubstitution and thus the loss of the targeted trainingstimulus. Strict form is essential, and the clinician mustcontinually monitor trunk, cervicothoracic, scapu-lothoracic, and upper extremity move-ments and posi-tioning until the patient gains the necessary awarenessof the proper mechanics for the exercise.

The goal of weight training is to increase andimprove all aspects of the neuromuscular system,including strength, power, and endurance withoutinjury. The challenge to both clinician and patient is tolearn proper technique in order that controlled, non-injurious, resisted movement can be consistently car-ried out. To accomplish these goals, a process must bedeveloped and adhered to at the beginning of exer-cise. We recommend the following training process:

1. Establish the range of motion. Start with a smallrange of motion and gradually increase the rangeof motion to points just short of compromisingtissue stress.

2. Establish the speed of motion. The emphasis is tolearn to move in a smooth, rhythmical, and con-trolled fashion without excessive pauses at eitherend of the range of motion or ballistic quick startsto the motion.

3. Complete the motion. Include as many of thearticulations of the shoulder girdle and trunk aspossible while maintaining control of the loads asthey pass into and through the injury. For example,in the seated row exercise, the motion can beginwith simple humeral movement, progress toinclude scapular protraction and retraction, andthen continue to include the entire coordinatedmotion of the trunk and shoulder girdle, which


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adds spinal flexion and resisted spinal extension tothe complete exercise. Starting with a simplehumeral extension and ending with compoundtrunk and shoulder girdle motion is most desirable.Note how the most comprehensive approach totraining the shoulder girdle involves monitoring theactivity of the muscles of the abdominal wall andextensors of the trunk.

4. Monitor substitution of motion. Once range ofmotion is established, the speed is constant, andcompound movements have been integrated, thenext step is to recognize the subtle signs of fatigueor what is referred to as “repetitions to substitu-tion.” Fatigue can be defined as performing consis-tent movement patterns against resistance untilchange in speed and/or range of motion is real-ized. Fatigue can take place in any represented partof the motion and over any articulation of theshoulder girdle. For example, during one exercisesession, the first muscle group to fatigue may bethe scapular retractors and those muscles responsi-ble for controlling the scapula. The patient recog-nizes the gradual changes in the position of hisscapula as it completes its excursion over the tho-rax. In a subsequent exercise session the fatiguemay not be in the scapula retractors but instead inprime movers associated with glenohumeralmotion. “Clinical” fatigue is a change of speed orchange in motion that alters the loading patterns ofeach involved tissue. Again, the role of the abdom-inal wall cannot be overemphasized.

Once the patient is appropriately instructed andinvolved in strengthening in this manner, the coordi-nation or control of weight bearing will be accom-plished, and each repetition and set of resistedexercises will appropriately stimulate the tissues. Wefeel that in a therapeutic condition, it is a mistake todevelop the exercise prescription that states “do 3 setsof 10 repetitions.” One day 10 repetitions might beexcessive for the tissue, resulting in injury, whereas thenext day 10 repetitions may be more easily toleratedand the training effect not even realized. This is espe-cially important in the rehabilitation of the shoulderbecause it is very easy to overstress the rotator cufftendons.

Once the patient comprehends this four-stepprocess, the chances of reinjury decrease markedly.The exercise prescription is then further developed tomeet specific training needs. The question becomes,“To what sport or activity of daily living is the patient

attempting to return?” Understanding the goal is obvi-ously a major component in determining the intensity,frequency, and duration of the rehabilitation process.Designing the rehabilitation to fit the task is ultimatelythe goal that we need to progress toward, closely repli-cating the movements and forces that mimic the activ-ity to which the patient expects to return. Effectivestrength training will result in neural and musculofas-cial changes.13,23

THE EXERCISE SECTION

A unique aspect of this text is marked by the inclu-sion of a comprehensive series of exercises that can beselected for many of the mechanical shoulder condi-tions that we have discussed. The sequence of exer-cises also includes clinical commentary regardingessential considerations for positioning, in addition topositions or movements that have the potential tocompromise a particular tissue or structure. This “set”of exercises is meant to serve as a “palette” fromwhich the clinician can make selections based ondesired outcome.

The exercise section provides an array of exercisesdesigned to improve the strength, power, andendurance of the global and local muscles associatedwith the shoulder girdle. The reader is encouraged torevisit Chapter 3 to understand where different mus-cle fiber crossing relationships occur because theseoften represent foci for resistance exercises. Suchcrossing relationships exist between the following:

● Latissimus dorsi and serratus anterior● Latissimus dorsi and gluteus maximus● Serratus anterior and abdominal wall bilaterally● Trapezius and rhomboids● Pectoralis major bilaterally● Long head of the triceps and the teres major and

infraspinatus● Coracobrachialis or short head of the biceps brachii

and the subscapularis

These regions of muscle crossing, with each otheror as a result of the muscle fiber direction when themuscles are considered bilaterally, are a focus forstrengthening exercises. This type of training comple-ments and enhances specific, localized strengthening,such as isolated rotator cuff strengthening. Isolatedstrengthening is an excellent point at which to intro-duce resistance exercises, but it is necessary for each ofthe shoulder girdle articulations to work in concert


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with the trunk and spine in order to optimize upperquarter function. Therefore the exercise section thatfollows illustrates therapeutic exercises essential forscapulothoracic, trunk, and spinal stability or motion,as well as those that cross the glenohumeral joint.Appropriately strengthening the tissues at the apex ofthese relationships enhances the ability to stabilize thetrunk and neuromuscularly “link” the extremities.

Closely examine the starting, midrange, and finish-ing positions for each of the exercises presented.Whereas one clinician may look at a particular exer-cise and recognize its utility for a specific clinical prob-lem, another may see the same exercise and considerit useful for a markedly different problem. Many timesexercises are categorized according to muscle groups(e.g., exercises for the anterior deltoid, exercises for thepectoralis major, exercises for the rhomboids). Thereader will appreciate after reviewing Chapters 2, 3,and 4 that no muscle group works in isolation regard-less of the exercise. Trunk, spine, scapula, andhumeral muscles are all required to serve as stabilizersor prime movers or contribute muscle forces, whichcancel the unwanted motions that the prime moverwould introduce to the desired movement pattern as aresult of its muscle fiber orientation.

We have organized this section to serve the clinicianseeking strengthening strategies for his patients and toillustrate exercises considered essential for generalconditioning of the upper quarter. The exercisesappear in the following order:

● Exercises 1 through 7. An excellent group of exercisesthat the clinician incorporates for the patient in theprone position to strengthen the scapular retractors

and those muscles of the glenohumeral joint associ-ated with pushing, pulling, and moving the armoverhead.

● Exercises 8 through 11. Seated resistance exercises forthe prime movers and scapular and trunk stabilizersinvolved with arm elevation.

● Exercises 12 through 15. Rowing exercises from differ-ent positions are some of the most useful exercisesfor strengthening the shoulder extensors, scapularretractors, and spine extensors.

● Exercises 16 through 18. The pull-downs and assistedpull-ups are powerful exercises for the latissimusdorsi, teres major, and the downward rotators of thescapula, such as the rhomboids.

● Exercises 19 through 35. Functional strengtheningexercises include the variations of the standing rowand pulling exercises. These exercises combine thestimulus of stabilization via the lower extremitieswith trunk and shoulder girdle movement.Depending on the instructions given by the clini-cian, these exercises can exert a training effect to thespinal extensors, abdominal muscles, and scapu-lothoracic and glenohumeral muscles.

● Exercise 36. The classic dumbbell curl.● Exercises 37 through 45. Pushing exercises are essential

for training the muscles of the anterior chest wall,the shoulder protractors, the abdominal muscles,and, with the arms beginning in the overhead posi-tion, the glenohumeral extensors.

● Exercises 46 through 48. Exercises emphasizing sen-sorimotor integration, quickness, and speed ofmovement.


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Beginning Position: Lie in acomfortable prone position with alight weight in hand. The tableheight permits complete scapularprotraction without weight touch-ing the floor. Retract scapula whilethe arm remains straight.Focus: Isolated and completescapular retraction.Sequence: A, B, A, B, A.

Exercise 1—Prone Lying Scapular Retraction

BA

Exercise 2—Prone Lying Humeral Extension and ScapularRetraction With Elbow Flexion

Beginning Position: Lie in a comfortable prone position with a light weight in hand. The tableheight permits complete scapular protraction without weight touching the floor. Extend humeruswhile flexing elbow and then retract the scapula. Perform one or more scapular retractions beforereturning to the starting position.Focus: Complete scapular retraction.Sequence: A, B, C, B, C, B, A.

B CA

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Exercise 3—Prone Lying Humeral Abduction

Beginning Position: Lie in a comfortable prone position with a light weight in hand. The tableheight permits complete scapular protraction without weight touching the floor. Abduct andexternally rotate the humerus to horizontal position and then retract the scapula. Perform one ormore scapular retractions before returning to the starting position.Focus: Complete scapular retraction and external rotation of the humerus.Sequence: A, B, C, D, C, D, C, B, A.

C

B

D

A

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Exercise 4—Prone Lying Forward Humeral Elevation

Beginning Position: Lie in a comfortable prone position with a light weight in hand. The tableheight permits complete scapular protraction without weight touching the floor. Forward elevateand externally rotate the humerus with final scapular upward rotation and retraction.Focus: Complete scapular upward rotation.Sequence: A, B, C, B, A.

B

C

A

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Exercise 5—Prone Lying Resisted Scaption

Beginning Position: Lie in a fully supported position on a table high enough that the arms canhang down freely. Flex, abduct, and externally rotate the humerus to the horizontal position.Hold arm position isometrically, pause, and then perform a few complete repetitions of scapularretraction and humeral external rotation. Pause and reverse.Focus: Externally rotating the humerus and the quality of scapular motion.Sequence: A, B, C, D, C, D, B, A.

C

B

D

A

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Exercise 6—Prone Lying Humeral Extension With Internal Rotation

Beginning Position: Lie in a comfortable prone position with a light weight in hand. The tableheight permits complete scapular protraction without weight touching the floor. Extend andslightly internally rotate humerus to the horizontal position, and then retract the scapula. Performone or more scapular retractions before returning to the starting position.Focus: Complete scapular retraction.Sequence: A, B, C, D, C, D, C, B, A.

C

B

D

A

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Exercise 7—Prone Lying Humeral Extension With External Rotation

Beginning Position: Lie in a comfortable prone position with a light weight in hand. The tableheight permits complete scapular protraction without weight touching the floor. Extend whileexternally rotating the humerus. Pause and retract the scapula. Perform one or more scapularretractions before returning to the starting position.Focus: Complete scapular retraction.Sequence: A, B, C, D, C, D, B, A.

C

B

D

A

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Beginning Position: Sit upstraight with a dumbbell in eachhand; scapulae are fully depressed.Elevate and retract scapulae, keep-ing arms straight. Pause andreverse.Focus: Isolating the motion tothe scapulae, and the last portionof scapular elevation and retrac-tion (up and back, squeeze).Sequence: A, B, A.

Exercise 8—Seated Scapular Elevation and Retraction With Dumbbells

BA

Exercise 9—Seated Humeral Forward Elevation

Beginning Position: Sit up straight with a dumbbell in each hand. Forward elevate and exter-nally rotate the humerus in the scapular plane until weights are overhead. Vary planes of motionfrom straight abduction to humeral flexion.Focus: External rotation of humerus during humeral forward elevation.Sequence: A, B, C, B, A.

B CA181

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Exercise 10—Seated Forward Elevation and UpwardRotation of the Scapula

Beginning Position: Sit up straight with a dumbbell in eachhand. Flex elbows and abduct humerus in scapular plane; pushdumbbells overhead. Keep forearms in a neutral position. Push thefront of the dumbbell up in a curvilinear motion, rotating thescapulae upward as high as possible (squeeze). Pause and retractscapulae, keeping arms straight. Repeat a number of times, thenreturn arms to the starting position.Focus: Isolating the movement to the scapulae and completing therange in forward elevation. The focal point is the interior angle ofthe scapulae.Sequence: A, B, C, D, C, D, C, B, A.

B

C

A

D

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Beginning Position: Sit upstraight with a dumbbell in eachhand; scapulae are fully depressed.Elevate and retract scapulae; ab-duct and slightly externally rotatethe humerus. Squeeze, pause, andreverse.Focus: Slight external rotation ofthe humerus after full scapularelevation (up and back, squeeze,pause, reverse).Sequence: A, B, A.

Exercise 11—Seated Scapular Elevation and Retraction With HumeralAbduction and External Rotation Using Dumbbells

BA

Exercise 12—Single-Armed Dumbbell Row

Beginning Position: Place one knee and ipsilateral arm on bench with other foot on the floor,and place dumbbell in the other hand with the left scapula fully protracted. Flex elbow, extendhumerus, retract the scapula, and slightly rotate trunk. Make sure to maintain the midrange posi-tion of the contralateral scapula and lumbar spine.Focus: Full scapular retraction.Sequence: A, B, A.

BA

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Exercise 13—Seated Row, High Range With No Spinal Motion

C

Beginning Position: Sit up straight with scapulae fully protracted. Extend the humerus andretract the scapulae (do not extend lumbar spine past the neutral position). Pull cable to eye level.Pause and reverse.Focus: The last portion of scapular retraction.Sequence: A, B, C, B, A.

BA

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Exercise 14—Seated Row, Midrange With Trunk Flexed

Beginning Position: Sit and bend forward with spine flexed and scapulae fully protracted.Slightly extend the head, pull the humerus and scapulae back, sit up straight (do not extend thelumbar spine past the neutral position), and retract (squeeze) both scapulae. Pull cable to lowerrib cage. Pause and reverse.Focus: The last portion of scapular retraction.Sequence: A, B, C, D, C, B, A or E, F, E.

B

A

E

D

C

F

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Exercise 15—Seated Row, High Range With Trunk Flexed

Beginning Position: Sit and bend forward with spine flexed and scapulae fully protracted.Slightly extend the head and neck, extend the humerus, retract the scapulae, and extend the spineto the neutral position (do not extend the lumbar spine past the neutral position). Pull cable highto eye level. Pause and reverse.Focus: The last portion of scapular retraction (squeeze).Sequence: A, B, C, B, A.

B

C

A

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Exercise 16—Latissimus Dorsi Pull-Down, Wide Grip

Beginning Position: Sit up straight and use wide grip; stabilize thighs under pad. Lean backand pull cable down to mid-chest. Pause and reverse.Focus: Pulling bar down in front, and scapular depression and retraction.Sequence: A, B, C, B, A or D, E, D.

BC

A

ED

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Exercise 17—Latissimus Dorsi Pull-Down, Narrow Grip

C

B

D

Beginning Position: Situp straight and use narrowgrip; stabilize thighs underpad. Lean back and pullcable down to mid-chest.Pause and reverse. NOTE:Compared with the widegrip lat pull-down, this posi-tion and movement can pro-duce more force and mayneed more resistance.Focus: Pulling handledown in front, and scapulardepression and retraction.Sequence: A, B, C, D, C,B, A.

A

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Exercise 18—Pull-Up, Gravity Assisted

Beginning Position: Stand on platform. Flex, abduct, and externally rotate humerus, andgrasp bar. Extend and adduct humerus, and downwardly rotate the scapulae. NOTE: This exer-cise requires specialized equipment that permits adjustment to counterbalance (minimize) bodyweight.Focus: Complete coordinated, smooth motion.Sequence: A, B, C, B, A.

B

C

A

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Exercise 19—Standing High Row, Midrange

Beginning Position: Stand with one foot forward and both scapulae fully protracted and ele-vated. Slightly flex trunk. Pull cable down to the zyphoid process of the sternum while transfer-ring weight to back foot and retract the scapulae. Pause and slowly reverse. Do not extend thelumbar spine.Focus: Retraction and downward rotation of the scapulae.Sequence: A, B, C, D, C, B, A.

C

B

D

A

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Exercise 20—Standing High Row, Low Range

Beginning Position: Stand with foot forward and scapulae fully protracted and elevated. Pullcable down to mid-thighs while transferring weight to back foot, pull rib cage slightly downtoward the top of the pelvis (crunch), and extend humerus and retract scapulae.Focus: Slight trunk flexion (crunch) and scapular retraction at the end.Sequence: A, B, C, D, C, B, A.ORFocus: Emphasize scapular depression and trunk flexion.Sequence: A, B, C, E, F, C, B, A.

B CA

E FD

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Exercise 21—Standing Two-Handed Diagonal High Row

Beginning Position: Stand facing pulley, then turn left to a 90-degree angle from the pulley.Reach up across with both hands (note hand placement) and pull cable down and across. NOTE:The motion is an 80% push with the top (right) hand and a 20% pull with the bottom (left) hand.Use varying degrees of motion. Slow down and even stop a few times during the eccentrics toenhance the training effect.Focus: Smooth and controlled weight transfer passing from the closest foot to the pulley to theback foot while flexing and slightly rotating the trunk with full scapular protraction.Sequence: A, B, C, D, C, B, A.

C

A

D

B

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Exercise 22—Standing One-Armed Diagonal High RowWith External Rotation

Beginning Position: Stand facing pulley, then turn left to a 90-degree angle from the pulley.Reach up across with scapula fully protracted and upwardly rotated. Pull cable down, high to low,extending and externally rotating the humerus while retracting and depressing the scapula androtating the trunk. Use varying degrees of motion.Focus: Smooth and controlled weight transfer, and scapular retraction and trunk rotation at the end.Sequence: A, B, C, B, A.

B CA

Exercise 23—Standing Mid-Row, Midrange

Beginning Position: Stand with one foot forward and both scapulae fully protracted. Pull thecable straight back to belt line while transferring weight to back foot. Pause and reverse.Focus: Full scapular retraction (squeeze).Sequence: A, B, C, B, A.

B CA

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Exercise 24—Standing Mid-Row, High Range

Beginning Position: Stand with one foot forward and both scapulae fully protracted. Pull thecable back and up to chin level, and squeeze the scapulae together. Pause and reverse.Focus: The smoothness of scapular motion and the tight squeeze at the end of the motion.Sequence: A, B, C, D, C, B, A.

B

C D

A

194

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Exercise 25—Standing Mid-Row, Low Range

D

Beginning Position: Stand with one foot slightly forward and scapulae fully protracted. Arms arestraight. While transferring weight from the front foot to the back foot, pull the cable to mid-thighsby extending and depressing the humerus and flexing the trunk (crunch) at the end.Focus: Humeral depression and crunch at the end.Sequence: A, B, C, D, C, B, A.

B

C

A

195

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Exercise 26—Standing One-Armed Mid-Row, Midrange WithExternal Rotation

Beginning Position: Stand facing pulley, then turn left to a 90-degree anglefrom the pulley. Reach across body with scapula fully protracted. Pull cablestraight across, extending and externally rotating the humerus, retracting thescapula, and slightly rotating the trunk. Use varying degrees of humeral motionand trunk flexion.Focus: Smooth and controlled weight transfer, and humeral external rotationand scapular retraction.Sequence: A, B, C, B, A.

BA

C

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Exercise 27—Standing One-Armed Diagonal Mid-Row WithIncreased Trunk Motion

C

Beginning Position: Stand facing pulley, then turn to a 90-degree angle from the pul-ley. Bend forward, side bend to the right, slightly rotate trunk to the right, and transferweight to the right foot with scapula fully protracted. Pull up and out, transferring weightfrom the right foot to the left foot and extending, abducting, and externally rotating thehumerus while at the same time retracting the scapula. Pause and protract the scapulaforward (lunge). Use varying degrees of motion.Focus: Smooth and controlled weight transfer, and scapular retraction, stabilization, andprotraction at the end.Sequence: A, B, C, B, A.

BA

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Exercise 28—Standing One-Armed Punch

Beginning Position: Stand facing away from pulley with one foot (left) forward, humerusextended, elbow fully flexed, scapula fully retracted, and trunk rotated to the right. Transferweight forward onto the front foot while performing a horizontal punch. Pause, then perform afew repetitions of scapular protraction before returning to the starting position.Focus: Smooth and controlled weight transfer and complete scapular protraction at endrange.Sequence: A, B, C, D, C, B, A.

C

B

D

A

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Exercise 29—Standing Low Row, High Range

Beginning Position: Stand with one foot forward and flex knee, hip, and lumbar and cervicalspine. Slightly extend the head, extend and abduct the humerus, retract and elevate the scapula,and pull cable to the middle of the eyes. Pause and reverse; return to starting position withsmooth and controlled motion.Focus: Spinal extension and smooth weight transfer.Sequence: A, B, C, D, E, D, C, B, A.

D

C

E

A B

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Exercise 30—Standing Low Row, Midrange

Beginning Position: Stand with one foot forward, slightly flex spine, and fully protract scapula.Slightly extend the spine, transfer weight to back foot, and retract the scapula while pulling cableto the belt line.Focus: Transfer weight to back foot without extending the lumbar spine past the neutral posi-tion and complete scapular retraction.Sequence: A, B, C, D, C, B, A.

C

B

D

A

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Exercise 31—Standing Low Row, Scapular Elevation

Beginning Position: Stand with neck and thoracic spine slightly flexed and scapulae fully pro-tracted, depressed, and downwardly rotated. Pull scapulae straight up and back. Pause andreverse. Permit elbows to flex only slightly.Focus: Elevating and retracting the scapulae.Sequence: A, B, A.ORBeginning Position: Stand with neck and thoracic spine slightly flexed and scapula fullydepressed and downwardly rotated. Pull scapulae up, flex elbows, and bring hands to the chin.Pause and reverse. Abduct while extending the humerus.Focus: Elevating and retracting the scapulae by emphasizing the final scapular “pinch.”Sequence: A, B, C, D, C, B, A.

C

B

D

A

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Exercise 32—Standing One-Armed Diagonal Low Row

Beginning Position: Stand facing pulley, then turn left to a 90-degree angle from the pulley.Flex and slightly rotate trunk to the right with scapula fully protracted. Pull cable up, low to high,extending and externally rotating the humerus, retracting and elevating the scapula, and rotatingthe trunk. Use varying degrees of motion.Focus: Smooth and controlled weight transfer, trunk rotation, and scapular elevation and retrac-tion at the end.Sequence: A, B, C, B, A.

B CA

Exercise 33—Standing Humeral Abduction, External Rotation

Beginning Position: Stand with one foot in front and dumbbell ineach hand, stabilize the trunk, and rotate humerus internally.Forward elevate and externally rotate the humerus and retract thescapulae. Begin moving in the scaption plane. Pause and return tothe starting position, making sure to internally rotate the humerusand touch the ends of the dumbbell. Vary the plane of motion.Focus: Scapular elevation and retraction and humeral rotation.Sequence: A, B, A.

BA

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Exercise 34—Standing Diagonal Low Row, Bilateral

Beginning Position: Stand in the middle and slightly back between two low pulleys.Slightly flex trunk, cross arms, and grasp opposite handles. Slightly extend trunk andabduct and externally rotate the humerus. Retract and elevate the scapulae. Be careful notto extend lumbar spine beyond the neutral position.Focus: Coordinated, smooth movement and complete scapular elevation and retraction.Sequence: A, B, C, B, A.

B

C

A

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Exercise 35—Seated Diagonal Low Row, Bilateral

Beginning Position: Sit on a chair or inflated ball between two low pulleys. Stabilize trunk andequalize weight between the pelvis and feet. Cross arms and grasp opposite handles. Abduct andexternally rotate the humerus and retract and elevate the scapulae. Pause. Be careful not toextend lumbar spine beyond the neutral position.Focus: Coordinated, smooth movement and complete scapular elevation and retraction.Sequence: A, B, A.

BA

Exercise 36—Seated Dumbbell Curls

Beginning Position: Sit on the edge of the bench or chair, one foot forward and the otherback. Shift weight forward over feet, dumbbell in each hand and elbows straight with wristspronated. Supinate and flex one elbow. As you lower arm, begin to flex the other arm. Learn todevelop a smooth (no pause) movement.Focus: Sustain trunk and scapular position.Sequence: A, B, A, B.

BA

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Exercise 37—Supine Flys

Beginning Position: Lie on a narrow bench with feet comfortably placed either on the flooror up on the bench. With a dumbbell in each hand, slowly lower the weight as the elbows flexand the humerus abducts to horizontal position. Push up while externally rotating the humerusand supinating the forearm slowly until the bottoms of the dumbbells touch. Pause and slowlyreturn to the horizontal position.Focus: Rotary motion required to touch the bottoms of the dumbbells. Do not go down beyondthe horizontal position.Sequence: A, B, C, B, C, B, A.

B CA

Exercise 38—Inclined Bench Press

Beginning Position: Lie on an inclined bench, holding a barbell across the chest. Push straightup and forward, making sure that the humerus tracks in midrange and the scapulae are com-pletely protracted. Pause and return to the horizontal position. Be cautious when extending thehumerus below the horizontal position.Focus: Complete scapular motion and full but safe range of humeral motion.Sequence: A, B, A.

BA

205

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Exercise 39—Diagonal Push-Ups

Beginning Position: Stand and lean on a high countertop or the wall. Start with scapulae fullyprotracted. Keep arms straight and fully retract and protract scapulae. Pause at the endrange.Focus: Complete protraction.Sequence: A, B, C, B, A.

B CA

Beginning Position: Use a medicine ball and assume apush-up position. Accomplish three movements: A, witharms straight, protract and retract scapulae, B, slowly flexthe elbows, lowering the chest toward the ball, and C,push up, making sure to fully protract the scapulae.Focus: Movement of the scapulae around the rib cage.Sequence: A, B, C

Exercise 40—Push-Ups

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Exercise 41—Supine Lying Resisted Humeral Extension

Beginning Position: Lie on a narrow bench with feet comfortably placed either on the flooror up on the bench with arms extended and holding a weight. Slowly permit the weight to fallback overhead. Take the weight to the desired endrange of motion. Permit the rib cage to rise.Pause and return by first pulling the rib cage, and then the arms, up to the starting position.Bending the elbows lessens the resistance.Focus: Abdominal activity at the rib cage, either isometric or dynamic.Sequence: A, B, A.

B

A

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Exercise 42—Supine Lying Resisted Humeral Extension, Combined

Beginning Position: Lie on a narrow bench with feet comfortably placed either on the flooror up on the bench and arms straight and holding a weight (dumbbell). Slowly permit the weightto fall back overhead. Take it to the desired endrange of motion. Permit the rib cage to rise. Pauseand return by first pulling the rib cage, and then the arms, up to the starting position. Continuethe movement by pushing the front of the dumbbell up in a curvilinear motion, rotating thescapula forward and upward. Tuck chin, slightly flex trunk, and complete the scapular motion(squeeze). Pause and retract scapulae, extend the humerus (keeping arms straight), and permit theweight to move overhead.Focus: Coordinated, smooth, complete motion. Focal point is the abdominal contraction (iso-metric or dynamic) at the rib cage and movement of the inferior angle of the scapulae.Sequence: A, B, A, C, D, C, A.

C

B

D

A

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Exercise 43—Supine Lying Scapular Protraction, Isolated

Beginning Position: Lie on a narrow bench with feet comfortably placed either on the flooror up on the bench. Hold dumbbells with arms straight. Push the front of the dumbbells up in acurvilinear motion, rotating the scapulae forward and upward. Tuck chin, slightly flex trunk, andcomplete the scapular motion (squeeze). Pause and retract scapulae, keeping arms straight.Focus: Isolating movement to and complete forward elevation of the scapulae. Focal point ismovement of the inferior angle of the scapulae.Sequence: A, B, A, B, A.

BA

Exercise 44—Upward Rotation of the Scapula

Beginning Position: Sit with dumbbell or on special equipment. Elevate humerus forward toapproximately 140 degrees. Push weight up and forward. Pause and return to straight arm position.Focus: Curvilinear motion isolated to the scapula. Focal point is the inferior angle of the scapula.Sequence: A, B, A, B, A.

BA

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Exercise 45—Supine Lying Resisted Push

Beginning Position: Lie on a narrow bench with feet comfortably placed either on the flooror up on the bench. Flex elbows and hold dumbbell close to chest. Extend elbows and protractthe scapulae. Slightly tuck chin, push weight in a curvilinear motion up, and pull rib cage downtoward the pelvis (crunch). Complete range of motion and return to the starting position, per-mitting weight to just barely touch chest.Focus: Coordinated, smooth, complete motion.Sequence: A, B, C, D, C, B, A.

C

B

D

A

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Beginning Position: Stand facing the inclined trampoline, one foot forward. With both hands, throwand retrieve a weighted ball into the trampoline. Vary the range of motion (high, low, side-to-side).Focus: Loads imparted to the shoulder and the smooth transfer of weight through the spine.Sequence: A, B, A, C, D, C, A.

Exercise 46—Resisted Functional Training (Tramp), Two-HandedStraight On

B

C

A

D

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Exercise 47—Resisted Functional Training (Tramp), One-HandedDiagonal With Isolated Movement

Beginning Position: Stand facing the inclined trampoline, then turn left to a 90-degree anglefrom the trampoline. Throw and retrieve a weighted ball into the trampoline. Vary the range ofmotion (high, low) and gradually use as much of the spine and lower body as possible.Focus: Loads imparted to the shoulder and the smooth transfer of weight through the spine.Sequence: A, B, C, D, B, C, A.

B

C

A

D

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Exercise 48—Resisted Functional Training (Tramp), One-HandedDiagonal With Full Movement

Beginning Position: Stand facing the inclined trampoline, then turn left to a 90-degree anglefrom the trampoline. Throw and retrieve a weighted ball into the trampoline. Vary the range ofmotion (high, low) and gradually use as much of the spine and lower body as possible.Focus: Loads imparted to the shoulder and the smooth transfer of weight through the spine.Sequence: A, B, A, B, C, A, B, A.

B

C

A

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CLINICAL EXAMPLES:PATHWAYS OF CARE FORSHOULDER DISORDERSCORRELATED WITH THEOBJECTIVES OF TREATMENT

Impingement Syndromes andDisorders Related to Soft Tissuesof the Coracoacromial Arch:Nonsurgical Management

We discussed the pathomechanics contributing toimpingement syndromes in previous chapters becausemany interventions focus on altering those mechani-cal factors that might contribute to compromise oftissues in the subacromial space. The problem arc istypically forward rather than lateral, with impinge-ment occurring against the anterior third of theacromion and inferior aspect of the acromioclavicularjoint. The structures most commonly involved are thesupraspinatus tendon, the anterior aspect of the infra-spinatus tendon, the bursal covering associated withthese two tendons, and the long head of the bicepstendon. Several biomechanical considerations guidethe clinician in the development of a comprehensivetreatment plan:

● Scapulothoracic muscle weakness contributes toincreased stress of the soft tissues in the subacromialspace through failure to provide scapular stability;muscle weakness results in a relatively downwardlyrotated position and protracted position duringshoulder motions, leading to subacromial impinge-ment.

● Glenohumeral joint capsular restrictions result inthe inability of the humerus to remain centered onthe glenoid during humeral movements and the lossof the ability of the glenohumeral joint to reach thedegree of external rotation required to allow thegreater tuberosity to be positioned behind theacromion process during overhead activities (seeChapter 4).

● Rotator cuff weakness or early fatigue of the cuffmusculature results in the inability of the muscula-ture to center and maintain the head of humeruswithin the glenoid fossa during glenohumeralmotion (see Chapter 3).

● Excessive tensile loading that may occur with decel-eration activities results in significant stress placedon the posterior rotator cuff muscles during thedeceleration phase of throwing, especially the

supraspinatus, infraspinatus, and teres minor; ten-don attrition begins, and tearing can be a sequelae.

The objective of treatment that is the primary focusduring the initial patient treatment session is effectivemodulation of pain. Pain and swelling must be controlledfirst before addressing the mechanics associated withimpingement. There are several ways to control painand the associated inflammatory response:

● Nonsteroidal antiinflammatory drugs (NSAIDs)● Ice, which is particularly effective following the

application of cross friction techniques● Phonophoresis or iontophoresis: these modalities

can be effective because the subacromial region ofthe shoulder is relatively subcutaneous; when apply-ing these modalities, the following patient position-ing should be considered in order to optimizeexposure of the medicinal ions:

1. Subacromial exposure—the best exposure iswith hand in small of back, but care must betaken that excessive adduction of humerus doesnot occur.

2. Biceps long head—the best exposure is with thehumerus in slight external rotation and hyperex-tension.

● Injection of inflammation reducing agents into thesubacromial space

● Grade I and II accessory mobilizations to providemechanoreceptor input into the joint, potentiallymodulating pain

The next objective of treatment to implement is theclinician’s application of passive and active stresses topromote and encourage pain-free, active movements by thepatient. This is an extremely important objectivebecause often it directly deals with the shoulder path-omechanics considered to be contributing factors tothe syndrome. The following list summarizes some ofthe most strategic interventions to consider:

● Stretching of the glenohumeral joint capsule in order toincrease all physiological motions, especially external rotation.External rotation of the glenohumeral joint isessential to clear the greater tuberosity from underthe head of the humerus during overhead motion;to be most effective with this passive stretching tech-nique, use varying degrees of flexion and abductionwith the stretches into external rotation.

● Accessory motion joint mobilization techniques of the gleno-humeral joint both in the neutral position and in varying


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degrees of glenohumeral elevation. The accessory mobi-lization maneuvers need to be translations ofthe head of the humerus on the glenoid in the ante-rior, posterior, and inferior directions. If the intentof joint mobilization maneuvers is to modulatepain, the techniques should be applied with theglenohumeral joint in the loose packed position. Ifthe intent is to increase the mobility of the gleno-humeral joint capsule, then the techniques shouldbe applied with the glenohumeral joint in varyingdegrees and planes of glenohumeral elevation.

● Stretching of pectoralis major muscle. This is indicated ifthe examiner notes adaptive changes of the soft tis-sues of the anterior shoulder girdle that are con-tributing to the forward head, rounded shoulderposture; an internally rotated humerus, such asmight occur with tightness of the pectoralis majormuscle, will increase compression under the cora-coacromial arch during any forward elevationmovements.

● Stretching of pectoralis minor. This might also be neces-sary as a result of the adaptive changes that occurwith a rounded shoulder posture; a protractedscapula would require an even greater range ofglenohumeral external rotation in order to provideclearance of the greater tuberosity from under theacromion during overhead movements.

● Mobilization of the scapulothoracic articulation for a hypo-mobile scapulothoracic articulation in superior-inferior,protraction-retraction, and upward rotation–downward rota-tion motions. Scapulothoracic hypomobility leads toincreased glenohumeral compression stresses associ-ated with repetitive overhead efforts.

There are several effective ways to stretch thesetissues, from the prolonged passive stretch and oscilla-tions for connective tissue structures to a contract-relax and hold-relax technique that affects theneuromuscular elements.

With the inflammatory process under reasonablecontrol, the clinician can initiate treatment to enhanceneuromuscular performance. Strengthening the rotator cuffmusculature is often the primary focus, although it isessential to prescribe strengthening exercises for themuscles of the scapulothoracic articulation, especiallythe scapula retractors, elevators, and upward rotators,and the extrinsic muscles of the shoulder girdle. Therationale for emphasizing the rotator cuff muscles is tooptimize their ability to maintain the central positionof the head of the humerus in the glenoid fossa dur-ing motions that bring the arm overhead. We often

prefer to begin with rotator cuff strengthening beforeinitiating strengthening of the extrinsic musclesbecause a weak rotator cuff in the presence ofstronger extrinsic shoulder muscles results in superiormigration of the humerus.

While isolated rotator cuff exercises can be a pointfrom which to begin a resistance exercise program forthe rotator cuff muscles, broad patterns of movementincorporating the intrinsic cuff muscles, extrinsicshoulder muscles, scapulothoracic muscles, abdominalmechanism, and spinal extensors are the most func-tional and practical way to progress the training effectfor the muscles. The general principles of strengthen-ing the rotator cuff muscles in the patient withimpingement syndrome are to emphasize correct formand positioning, to stay within the pain-free range, tocarefully observe the weight and repetitions to avoidmuscle substitution, and to progressively incorporateeccentric activities in a carefully monitored manner. Iftears of the rotator cuff muscles have already devel-oped as a result of chronic deceleration stresses orimpingement, the clinician must cautiously overloadthe muscles because a consequence of excessive over-load may be an even greater tear of the rotator cuff.

Exercises mentioned in Chapter 3 and earlier in thischapter have an important training effect on the rota-tor cuff muscles. The specific muscles and related exer-cises considered to have an excellent training effect onthem when monitored closely and performed withexacting shoulder girdle and trunk mechanics include:

● Supraspinatus. Military press activities and scaptionexercises, both performed with the humerus inexternal rotation, are excellent functional exercisesfor training this muscle (we do not use an internallyrotated glenohumeral joint position for any resistedshoulder elevation exercise).

● Subscapularis. Scaption exercises take advantage ofthe subscapularis function of centering the humeralhead; additional exercises include internal rotationagainst the resistance of free weights or pulleys, mil-itary press exercise with the humerus maintained inexternal rotation, and shoulder flexion exercises.We prefer to avoid any positions of overheadmotion against resistance without the humerusbeing maintained in external rotation. When themuscle fiber orientation of the subscapularis isclosely examined, it is clear that pulling the armdown and across the body against resistance incor-porates the trunk, extrinsic shoulder muscles, andintrinsic subscapularis muscle.


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● Infraspinatus and teres minor. Horizontal abductionwith external rotation, external rotation againstresistance, scaption with external rotation, andshoulder deceleration exercises are all excellentways to introduce a specific training stimulus tothese key posterior cuff muscles.

Often the clinician prescribes exercises using resist-ance tubing or other elastic resistance. Use such exerciseequipment cautiously with suspected rotator cuffinjuries in impingement conditions because the resist-ance the tubing offers increases throughout range ofmotion. Thus the resistance force of the elastic increasesas the muscle begins to lose its efficiency in the motion.This may place excessive stress on injured tissues.

Strengthening of scapular muscles is an essentialbut often overlooked aspect of exercise in the man-agement of impingement disorders. The rationale foremphasizing strong upward rotators of the scapula isto ensure that the coracoacromial arch of the scapulamoves up and away from the humeral head duringshoulder motion. The primary upward rotators of thescapulothoracic articulation are the serratus anteriorand the force couple provided by the upper and lowertrapezius muscles.

Several exercises can be incorporated to maximizethe training effect to specific muscles of the scapu-lothoracic articulation:

● Serratus anterior. “Bench press,” or pushing motionsagainst resistance with a strong protraction at end ofmotion; a push-up “plus,” which is a standard push-up incorporating a strong protraction at the end ofthe motion; pullover exercises from the supine posi-tion; and complete shoulder arcs of motion throughfull range using light weights in order to emphasizeupward rotation of the scapula are excellent exer-cises for the serratus anterior. The patient must beclosely monitored with any exercises that requirethe humerus to elevate above the horizontal planein order to avoid exacerbation of an impingementproblem.

● Trapezius, rhomboids, and levator scapula muscles.Shoulder shrugs, scapula retraction pulling exer-cises such as one-arm rowing, emphasize thescapular retraction component of bilateral rowsand pull downs; proprioceptive neuromuscularfacilitation (PNF) patterns, which focus on scapu-lar motion and setting of the scapula, are alsoeffective manual resistance exercises for thesemuscles as well.

The remaining objective of treatment refers topatient education in the form of biomechanical counseling. Bythis, we mean teaching the patient those motions,positions, and activities that potentially compromisethe soft tissues involved with the impingement syn-drome. Very often the instructions given to thepatient for this condition must be sport or occupa-tion specific. For example, advise swimmers todecrease internal rotation of the arm as it enters thewater (thumb should not enter water first), decreasetheir body roll during the freestyle and backstroke,and increase their body lift during the butterflystroke. In addition, advise them to avoid using handpaddles because of the potential increased stress as aresult of increased lever arm length acting over theshoulder.

In athletes involved in throwing sports, closely mon-itor the number of throws, pitches, the velocity of thethrow, and the distance thrown. It is often wise toprogress a thrower from gentle “lobs” to throws ofincrementally increasing distance.

Teach overhead workers in the industrial setting topay close attention to scapular strength, how muchoverhead work is being done, and how much repetitivestress occurs in their workstation. Small adjustments inthe workstation can significantly change the stresses tothe tissues of the shoulder, especially if the workrequires prolonged overhead positioning or repetitiveoverhead motions.

Postsurgical RehabilitationConsiderations Related toImpingement Disorders: RotatorCuff Tears and SubacromialDebridement

Surgery for shoulder impingement disorders isgenerally reserved for conditions classified as stagesII and III in the Neer classification scheme for shoul-der impingement (see Table 5-2). Decisions to oper-ate on Stage II disorders are often reserved for thepatient over 40 years of age. Types of surgery per-formed to decompress the suprahumeral spaceinclude excision of anterior third of acromion,release of coracoacromial ligament, rotator cuff ten-don debridement, and bursectomy. The variability ofthe surgical approach, coupled with the varyingdegrees of cuff and subacromial debridement orreconstruction performed, makes a general discussionof rehabilitation difficult.


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For ease of discussion, we will describe the rehabil-itation concepts behind three surgical approaches ofincreasingly greater tissue disruption:

1. Arthroscopic debridement of the subacromialspace

2. Arthroscopic debridement of the subacromialspace and open cuff repair through separation ofthe fibers of the deltoid

3. Open repair via detachment of the deltoid from itsclavicular and anterior acromial attachments

We have summarized the surgical approaches inthis manner to emphasize that the rehabilitation foreach of these varies not only in terms of time lines butalso in the aggressiveness with which the patient canpursue active exercise and resistive exercise and returnto sport or activities of daily living. Postsurgery reha-bilitation for each of these patients begins with com-munication with the surgeon in order to gain anunderstanding of the specific tissues and the health ofthose tissues involved in the surgery. In all three con-ditions, the patient must understand that continuinghis exercise program is essential for his condition, evenafter completing his course of rehabilitation.

In the postsurgical management following arthro-scopic debridement, a more rapid recovery is expectedbecause the deltoid attachment has not been compro-mised. We begin passive and active assistive motionimmediately following surgery with a particularemphasis on external rotation. When performing pas-sive glenohumeral elevations in any plane, we apply avery small inferior glide simultaneous with the eleva-tion movements. Rotation exercises are relatively safewithin the first 30 degrees of glenohumeral elevation,but above that level the clinician must carefully moni-tor rotations because they can simply “grind” the cufftendons within the subacromial space.

Isometric exercises for the extrinsic and intrinsicshoulder muscles are also initiated immediately aftersurgery. When range of motion is full and relativelypain free, we then commence the use of free weightsand pulleys to progressively strengthen the intrinsic,extrinsic, scapulothoracic, and trunk muscles.Depending on the degree of tissue surgically debridedor repaired, patients can typically return to full activ-ity at 3 to 5 months if range of motion is full and painfree and optimal muscular strength and endurance arepresent.

If open repair of the rotator cuff is performed concurrentwith an arthroscopic debridement, the surgical approachtypically splits the deltoid along the lines of its fibers

rather than detaching it from its origin. Consequently,there is more tissue disruption than with arthroscopyalone but less than in open procedures that take downthe deltoid.

The rehabilitation time line is also determined bythe viability and size of the tendon defect repaired.Older tendon tears do not present the surgeon with anoptimal amount of tendon tissue to reattach to thehumerus, and the size of the tendon tear is one of thedetermining factors of healing time. Consequentlythe tendon repair of a large defect is not as strong andcannot be stressed as early or as vigorously as a repairof a smaller, acute tear in a younger individual.

Immediately after surgery the patient uses a shoul-der sling for the first few weeks to counter the gravita-tional stress of the humerus on the glenoid and tominimize motion. We typically begin mild isometricexercises and careful passive and active assistive rangeof motion exercises within a pain-free range duringthis healing period. Range-of-motion exercises remainthe essential aspect of treatment during the first 2 to 3months, and depending on the strength and size of therepair, strengthening exercises can be progressed usinglight resistance through controlled motions at the 3- to4-month mark. Typically a more advanced exerciseprogram for all of the shoulder muscle groups is notinitiated until the fourth or fifth month, but during thistime, the clinician is closely monitoring the gains inrange of motion and working to ensure that a fullrange of pain-free motion is present before anyaggressive strengthening regimen is initiated. Again,the size of the repair and viability of the tissue, cou-pled with the activity or sport the patient is returningto, determine the time frame at which he can return toactivity. Patients with a smaller, acute repair may beable to return to activity following gain of full motionand neuromuscular performance in 5 to 6 months,whereas patients with repairs at the opposite end ofthe spectrum may not be able to return to activity for9 to 12 months.

The open repair of the cuff tendon in which the del-toid is detached to present a larger subdeltoid field fea-tures the greatest tissue disruption discussed. As such,the shoulder joint must be protected to a greaterextent early on, and stresses to the repaired tissuesmust be introduced in a very controlled manner.

The early aspects of rehabilitation primarily consistof passive and very guarded active assistive range ofmotion for the first 2 to 3 months, depending on thesize of the repair. Depending on the degree of tissuedisruption, we do not typically begin resistance


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exercises until the third or fourth month, again basedon the surgeon’s opinion of the strength of the repair.Return to activity often takes 1 year or more becauseof the length of time needed for optimal tissue fixationand the return of fully functional shoulder motion andneuromuscular control.

Nonsurgical Managementfor Shoulder Instability

Several factors determine the aggressiveness oftreatment for individuals who have instability of theglenohumeral joint. Combinations of the factorsnoted below warrant caution in the early stages ofmanagement:

● Can the examiner detect excessive translation withpassive translational stresses?

● Is the anterior glenoid rim palpably tender?● Is there a suspicion of anterior rim of labrum

involvement (palpable tenderness; clicks and popsanteriorly)?

● What has been the frequency of dislocations andresultant reductions, and how many have occurred?

● Does arm transiently “go dead,” and is there sud-den pain with subluxation?

● Is there an associated impingement phenomenon?

The body type and onset of instability also guidethe clinician in selecting the most appropriate treat-ment regimen. Shoulder instability problems can becharacterized as:

● Atraumatic: the patient with general hypermobility,lax connective tissue framework, often female, withgeneralized weakness and poor posture

● Microtraumatic: the 15- to 35-year-old athlete orworker whose activities require much overheadmovement that results in gradual stretching of con-nective tissue restraints (usually this patient has asso-ciated pathology such as impingement or overusesyndromes)

● Traumatic: the patient with a single, identifiable,initial episode of dislocation of the glenohumeraljoint that may now have resulted in recurrentepisodes of dislocation

The use of a nonsurgical rehabilitation programfor shoulder instability depends on such factors asthe severity of the glenohumeral joint injury, the fre-quency of dislocations and subluxations, the age andactivity level of the patient, and the status of the

surrounding tissues, particularly the rotator cuffmusculature. If connective tissue structures such asthe glenohumeral joint capsule and the gleno-humeral ligaments are excessively lax or the glenoidlabrum is torn or partially avulsed from the glenoid,there is little chance that exercises can result incomplete stability of the glenohumeral joint.Perhaps more than in any of the other shoulder syn-dromes, the patient must clearly understand theimportance of his participation throughout therehabilitation process and be willing to avoid ordecrease those activities that render the shouldervulnerable to subluxation or dislocation.

As with the impingement syndrome, it is useful toplan the interventions along the four objectives oftreatment. If pain is a primary complaint, then thefirst objective is to address modulation of pain.Modalities to desensitize the region include ice or elec-trical stimulation and the use of NSAIDs. The con-cept of “active rest” also becomes important withinstability problems. Motion within very controlledranges while the pain settles is important in this painmodulation phase.

The clinician’s application of passive and active stressesto promote and encourage pain-free, active movements by thepatient must be applied in a very judicious manner.Aggressive stretching and joint mobilization have veryfew indications with an instability problem becausethis problem is primarily one of decreased stabilitybetween the humerus and the glenoid. If a forwardhead, rounded shoulder kyphotic posture is present, itmay be necessary to inspect the length of anteriorchest muscles but avoid specific stretches to the gleno-humeral joint structures. Likewise, mobility exercisesand stretches for the lower cervical and thoracic spine,especially thoracic extension, may be necessarybecause limitations of motion in the spine increase themotion requirements for the glenohumeral jointduring overhead activities.

Following an acute injury of the glenohumeral jointthat has resulted in instability, it is important to initiateisometric exercises to the rotator cuff and extrinsicmuscles of the shoulder early in the rehabilitationprocess. Isometric exercises should not exacerbate thepain and are well tolerated by the patient. Instruct thepatient to perform them in ranges of motion that donot compromise the weakened connective tissues. Thepurpose of such isometric exercises is to prevent atro-phy of the cuff muscles and to place very controlledforces through the joint capsule through the actions ofthe rotator cuff.


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Enhancing neuromuscular performance is one of themore important objectives in management of thepatient with shoulder instability. The primary focus oftreatment with instability disorders of the gleno-humeral joint is enhancing the strength, power, andendurance of the intrinsic and extrinsic musculatureof the shoulder girdle complex. In addition to theimportant rotator cuff muscles, exercises for the pow-erful extrinsic muscles of the shoulder, such as thelatissimus dorsi, deltoid, pectoralis major, coraco-brachialis, and biceps brachii, and for the muscles ofthe scapulothoracic articulation, such as the trapez-ius, levator scapula, rhomboids, and the serratus ante-rior, must be included (see Chapter 3 and previouslyin this chapter).

As noted in Chapter 3, it is also essential for the cli-nician to incorporate exercises that increase strengthof the trunk and lower extremities because of the link-ages between the muscles and through the key fascialsystems. Although many different exercises have beensuggested for strengthening the shoulder girdle, weprefer to use diagonal patterns against resistancethrough the invulnerable ranges of motion becausethese exercises incorporate trunk muscle activation(abdominal mechanism and spinal extensors), scapulamuscles, extrinsic shoulder muscles, and the rotatorcuff. While there has been a tendency in the past tofocus on the anterior shoulder muscles with the morecommon anterior subluxations and dislocations,strengthening of the external rotators, particularly theinfraspinatus and teres minor complex, is the morelogical focus for managing anterior instability (seeChapter 3). Ultimately, a global approach incorporat-ing total shoulder girdle and trunk strengthening is themost comprehensive treatment strategy.

The use of rhythmic stabilization exercises in vary-ing ranges of motion is very effective in the nonsurgi-cal management of instability.1 In the later stages ofrehabilitation, exercises against resistance and co-contraction exercises can be performed from theapprehension position with the intent being to developkinesthetic and proprioceptive awareness of vulnera-ble shoulder positions and the appropriate neuromo-tor responses to such positions. Plyometric exercisesusing varying sizes and weights of medicine balls arealso effective ways to train the neuromuscular complexabout the shoulder and are especially effective in deal-ing with athletes.27

During the physical examination (see Chapter 5) theclinician gains information regarding the vulnerableand invulnerable positions of the shoulder and the ease

with which the humerus translates over the glenoid.This allows for the careful planning of the motions andpositions relative to the glenohumeral joint for safe andeffective strengthening programs. This is the essentialaspect of enhancing neuromuscular performance withshoulder instability: overloading and challenging theneuromuscular system but not overwhelming thealready compromised specialized connective tissues.We recommend beginning the development of theexercise prescription using the invulnerable ranges ofmotion and carefully progressing to more functionalranges during the course of rehabilitation. The patientmust understand that no matter how strong or howhypertrophied the musculature becomes, most likelythere will be portions of the range that have the poten-tial for subluxation or dislocation.

Biomechanical counseling in the nonsurgical manage-ment of instability disorders requires that clinicianand patient carefully assess activities of daily living,work postures and requirements, and sport activities inorder to determine the limits of motion and loadingpatterns to the shoulder. The patient also is counseledto avoid the slumping postures and the glenohumeralapprehension position (abduction and external rota-tion) with sleeping.

Part of the educational process for a patient withinstability is that he realize the strengthening programfor his shoulder is not just a temporary phenomenon.Because of the high incidence of rotator cuff ten-donitis and impingement related disorders associatedwith glenohumeral joint instability, an exercise pro-gram must be maintained even after pain has sub-sided.9,12 Shoulder and trunk exercises need to becontinued on a regular and habitual basis.

Surgical Management for ShoulderInstability and PostsurgicalConsiderations

Numerous procedures have been described to surgi-cally stabilize the glenohumeral joint. The clinicianneeds to understand the extent and type of surgicalprocedure performed, because each has its own set ofunique precautions and protocols that influence therehabilitation process.

The general principle behind surgical proceduresdesigned to enhance the stability of the glenohumeraljoint is to directly restore the anatomy, particularly theglenohumeral joint capsule, glenohumeral ligaments,and glenoid labrum, to as normal an anatomical


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relationship as possible or to use the surrounding tis-sues to support the glenohumeral joint and minimizeaberrational movement between the humerus and theglenoid fossa. The challenge is to bolster the stabilityof the joint but still maintain functional range ofmotion and strength throughout the range of motion.

Anatomical reconstruction of the compromisedtissues, specifically the glenohumeral ligament com-plex and glenoid labral tears, can be accomplishedusing open or arthroscopic procedures. The size andextent of these lesions have become better recog-nized with the increasing use of diagnosticarthroscopy. The greater the extent of repair neededto the glenohumeral ligament and labral complex,however, the smaller the potential to effectively reachall of the necessary tissue via the arthroscope,increasing the necessity for an open repair. In addi-tion to labral reattachment, capsular shift proce-dures are designed to tighten the joint capsule,thereby removing the slack and redundancy from thecapsule-ligament complex.

The rehabilitation process uses each of the fourobjectives of treatment, and the timing of the intro-duction of each objective depends on many factorssuch as the presurgical status of the tissue, viability oftissues involved with the surgical procedure, and thetime frames associated with surgical healing. Pain andswelling are controlled immediately after surgerythrough the use of a sling and scaption support, whichplaces the glenohumeral joint at approximately 30degrees of scaption plane motion and 30 degrees ofexternal rotation. This helps protect the surgicallyrepaired capsulolabral complex.

During the first 2 months of rehabilitation the pri-mary focus is on passive and active assistive range ofmotion (application of controlled stresses). The clini-cian must have a keen tactile sense of end feel duringany passive motions and be able to clearly discernmuscle guarding from connective tissue tension. Theconnective tissues are gently “coaxed” out toward fullmotion. While all patients present as unique cases, wetypically strive to have full range of motion reached by2 to 3 months.

Strengthening (enhancing neuromuscular perform-ance) is begun with light isometric exercises at approx-imately the second or third week. As the patient makesgains in the range of motion, we encourage isometricmuscle strengthening in these newly gained ranges.Usually by the end of the first month the patient canalso perform light resistance exercises through varyingarcs of acquired motion. The clinician must monitor

the patient to avoid placing excessive stress on theanterior capsule, so we typically do not position thepatient in any way that might result in the arm beingpulled into uncontrolled external rotation by any freeweight, pulley, or medicine ball. It is important at thistime also to monitor the contribution of the scapu-lothoracic and trunk muscles to the motion carefullybecause these are integral components of thestrengthening program.

Finally, patient education (biomechanical counsel-ing) is important. The patient must understand theimportance of a long-term commitment to his exer-cise program. He must also understand the activitiesand positions that can compromise the repair.Throwing especially increases loading to the repairedtissues, and while gentle lob throws can be started atapproximately the eighth or ninth month, full speedthrowing must often be delayed for about a year aftersurgery.

Another surgical approach that attempts to dealdirectly with the lax capsular tissue is thermal capsu-lar shrinkage. The postsurgery rehabilitation plan forthis procedure includes passive range of motion ofglenohumeral joint to tolerance, including externalrotation with the glenohumeral joint placed at 45degrees abduction during the first month. Passivetechniques are followed by the initiation of antigravitymotion as tolerated. Posterior-to-anterior accessoryjoint mobilization techniques are carefully avoided inorder to minimize any forces against the anterior wallof the joint capsule. Submaximal resistance exercisesare used with a particular emphasis on rhythmicstabilization.

After the first month we include active and passiverange-of-motion exercises to tolerance, includingaccessory mobilizations. Posterior capsule stretchesare incorporated using across-the-body horizontaladduction, but care must be taken to stabilize thescapula in order to properly and completely applysuch a stretch. Resistance exercises using light weightsand pulleys are initiated with scaption plane elevationsand external rotation in varying positions of gleno-humeral abduction and flexion. Along with thestrengthening programs noted, exercises that ulti-mately incorporate the combined actions of the trunk,scapulothoracic articulation, and glenohumeral jointare the eventual goal. The key is to monitor symptomsand recognize the healing constraints of the surgicallymanaged tissues.

Several other surgical procedures do not deal withthe involved connective tissues directly but instead


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seek to offer increased joint stability by using sur-rounding bone or muscle tissue to provide a physicalrestraint to excessive glenohumeral translation. Thesetechniques are used less often today because of recentadvances in arthroscopic and open techniques to thecapsule and labrum but are presented here for the sakeof completeness.

The Bristow procedure, in which the tip of thecoracoid process, with the attached short head of thebiceps brachii and coracobrachialis, is removed andthen reattached to the anterior aspect of the glenoid,is one such surgical approach.24 The bone (coracoid)and muscular sling (biceps and coracobrachialis) cre-ate a barrier to anterior subluxation of the humerus.Limitations in external rotation typically occur withthis surgery, and the clinician must be cognizant ofexercises, especially resistance exercises, that mayplace increased loads through the biceps or coraco-brachialis muscles.

The Putti-Platt procedure uses the subscapularismuscle to reinforce the anterior aspect of the gleno-humeral joint. The subscapularis tendon is dividedmedial to its insertion, allowing a medial and lateralflap of subscapularis muscle to then be overlappedand attached to the anterior aspect of the joint to pro-vide an additional restraint to anterior subluxation.Like the Bristow, the Putti-Platt often results in limitedrange of motion, especially external shoulder rotation,and a loss of strength.21 In addition, excessive tighten-ing of the subscapularis has been attributed to pro-moting early degenerative joint changes in theglenohumeral joint.11

SUMMARY

We have provided treatment techniques, as well as athought process to organize a treatment approachalong the four objectives. Although there are manydifferent treatment techniques, the similarity in tech-niques lies in their purported effects. Thus, asreviewed early in this chapter, it is the intended effector intent of treatment that is most important in the devel-opment of a treatment program. When treating apatient with shoulder problems, it is important to rec-ognize the following as essential aspects: range ofmotion of the glenohumeral joint, strengthening ofthe rotator cuff musculature, strengthening of theextrinsic musculature of the shoulder, strengthening ofthe scapulothoracic muscles, and strengthening of thetrunk musculature. Regardless of the clinical problem

that is seen, these five aspects remain the mainstays ofsuccessful shoulder rehabilitation.

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7. Flowers KR, LaStayo PC: Effect of total end range time onimproving passive range of motion, J Hand Ther 7(3):150,1994.

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10. Hardy MA: The biology of scar formation, Phys Ther69(12):1014, 1989.

11. Hawkins RJ, Angelo RL: Glenohumeral osteoarthritis: a latecomplication of the Putti-Platt repair, J Bone Joint Surg Am72(8):193, 1990.

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13. Komi PV: Training of muscle strength and power: interactionof neuromotoric, hypertrophic, and mechanical factors, IntJ Sports Med 7(Suppl):10, 1986.

14. Larsson SE, Bengston A, Bodegard L, et al: Muscle changes inwork related chronic myalgia, Acta Orthop Scand 59:552, 1988.

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INDEX

AAbdominal fascia, 86Abdominal musculature

crossing relationships of, 50t, 86frelationship to the shoulder girdle of, 86-87, 87f,

87t, 121Acromioclavicular disc, 7tAcromioclavicular joint, 114-119, 161

connective tissues of, 116-117degenerative conditions of, 115, 119examination of, 121f, 142, 147, 157-158exercises for, 115, 117finjuries to, 14-15, 15f, 118-119, 120tneuroanatomy of, 41-45pain from, 119, 121f, 137role of, 58sprains of, 32stability of, 55, 116-118subluxation or dislocation of, 34f

Acromioclavicular joint capsule, 7tAcromioclavicular ligament, 69Acromion

ossification centers in, 93role of, in glenohumeral joint compression, 70-71suprahumeral-subacromial interface of, 107-114

Active compression test, 149, 151fAdhesive capsulitis of the glenohumeral joint, 106-107

age factors in, 134aggravating factors in, 138inflammatory processes in, 155-156treatment of, 122

Adipose tissue, 7fAfferent input, 169Age-related injuries, 133-136. See also rotator cuff

injuries.adhesive capsulitis of the glenohumeral

joint, 134connective tissue degenerative changes, 2-3degenerative conditions, 115frozen shoulder, 134impingement syndrome, 134tinstability syndromes, 133involving tendon tissue, 70-71referred pain in, 25-26, 27trole of proteoglycan in, 9-10of the rotator cuff, 70-71, 134

AMBRI. See atraumatic etiology with multidirec-tional instability pattern (AMBRI).

Analgesic drugs, 168Anatomical diagnosis, 129Anatomy of the shoulder. See musculature of the

shoulder.Anterior deltoid, 83Apophyseal joint degeneration, 24-26, 27tApplied physical stress concepts, 130-131Applied physical stresses, 130Apprehension tests, 157Arthritis of the glenohumeral joint, 18, 19f, 19tArthroscopy

for diagnostics, 130, 149, 158in surgical treatment, 217, 220

Articular cartilage, 8degeneration of, 2, 18of the shoulder complex, 7f, 18, 19f

Assessment. See evaluation of the shoulder.Page numbers followed by f indicate figures;t, tables.

223

W9272-Index.qxd 8/20/03 7:18 PM Page 223

Atraumatic etiology with multidirectional instabilitypattern (AMBRI), 137, 138

Axilla, 7, 30-31Axillary nerve, 37t, 41, 42f, 77f

examination of, 34-35, 37tinjuries to, 34-35, 137

BBankart lesion, 99, 100-101f, 137Barrier positions, 162-163Biceps brachii, 25t. See also long head of the biceps;

short head of the biceps.crossing relationships of, 50t, 73, 77fhanger function of, 78ftendons of, 17, 18f, 49, 72f

Biceps tendonanatomy of, 18f

Bicipital tenosynovitis, 85Biomechanics of connective tissues, 10-14

under repetitive loading, 12-13, 13fin rotator cuff tendon failure, 13-14

Biomechanics of throwing, 135tBlazina classification of pain, 139tBody types and function of the shoulder

joint, 4-6Bones of the shoulder complex, 7t, 8Brachial plexus, 22, 26, 28-30, 32f, 137

Erb’s point, 30, 31finjuries of, 28, 29f, 32-33neurophysiology of, 30-31peripheral nerves of, 31-35thoracic outlet syndrome, 35-38, 39f, 40f

Bursae, 7tof the rotator cuff, 108of the scapula, 76of the scapulothoracic interface, 121subacromial, examination of, 149-150

CCalcified tendonitis, 161Cancer, history of, 133Capsular ligaments. See glenohumeral joint

capsule.Capsulitis, 137Cervical apophyseal joint capsule, 7t

examination of, 27freferred pain from, 25-26

Cervical nerve rootsexamination of, 137, 138tirritation of, 22, 24-25

Cervical plexus, 41, 42f

Cervical spine, 7t, 22-25discogenic pain in, 26examination of, 27f, 141-142nerve roots, irritation of, 22, 24-25nerve roots, pain of, 24-25nerve root screen of, 24-25, 25treferred pain from, 25-26screening of, 24-26, 25t, 27fspinal accessory nerve (cranial nerve XI), 35,

38f, 39fCharacteristics influencing muscle function, 48tChronic pain syndrome, 131Clavicle, 7t, 147. See also acromioclavicular joint.Clinical examples, 214-222

of coracoacromial arch disorders, 214-216of impingement syndromes, 214-216of nonsurgical treatments for instability,

218-219of surgical treatments for instability, 219-221

Closed kinetic chain for strengthening, 95Clunk test, 149, 150fCollagen fiber, 8, 9f

crimp in, 10-11, 10fstress and strain on, 10-12, 11f

Complex regional pain syndrome, 161Compression of the connective tissues, 4, 6, 49,

130-131, 146Connective (soft) tissue injuries, 161

age-related degenerative changes in, 2-3applied physical stresses evaluation of, 130-131compression of, 4, 6, 49examination of, 131-132, 146, 155immobilization of, 3laxity and, 155subluxation of the humeral head in, 4, 6treatments for, 169, 170f

Connective (soft) tissues, 6-14anatomy of, 3-4biomechanics of, 3-4, 10-14distinguishing charachteristics of, 8intercellular components of, 8-10modification of, 169under repetitive loading, 12-13specialized types of, 6-8, 7t, 10-14stress and strain on, 10-12

Controlled loading, 12-13, 162Coracoacromial arch disorders, 214-216Coracoacromial ligament, 7t

deformities of, 110-111in rotator cuff tears, 74fsuprahumeral-subacromial interface, 107-108

224 INDEX


Coracobrachialis, 25t, 72, 83-84crossing relationships of, 50t, 73, 77fhanger function of, 78fsuprahumeral-subacromial interface, 107-108

Coracoclavicular ligament, 7t, 81f, 117, 118fCoracohumeral ligament, 7t, 70, 72f, 106Corticosteroid injections, 168Costoclavicular ligament, 7t, 81fCounterbalancing of the shoulder, 74-75, 76f,

78f, 80tCranial nerve XI (spinal accessory nerve), 35, 38f, 39fCrossing relationships, 50, 50t, 73-75

of the abdominal musculature, 86fof the coracobrachialis, 50t, 73, 77fof the deltoid, 74of the glenohumeral joint, 77fof the gluteus maximus, 50t, 52-53of the infraspinatus, 50tof the latissimus dorsi, 50t, 52-53of the long head of the biceps, 50tof the long head of the triceps, 50t, 73-74, 77fof the pectoralis major, 74-75, 82f, 83of the rhomboids, major and minor, 50tof the serratus anterior, 50t, 52-53of the short head of the biceps, 73of the short head of the biceps brachii, 77fof the subscapularis, 50t, 73, 77fof the teres major, 50t, 77fof the trapezius, 50t

DDegenerative joint disease, 26Deltoid, 25t, 64, 71-73

counterbalances of, 73, 76fcrossing relationships of, 74hanger function of, 78fmechanics of, 110, 111fthree heads of, 75f

Dense connective tissue, 7Diabetes, 156Diagonal push-ups, 206Diaphragm, 86fDiscogenic pain, 26Dislocation of the glenohumeral joint, 2, 99. See also

subluxation of the humeral head.clinical examples of, 218-219peripheral nerve injuries resulting from, 137superior labrum anterior to posterior (SLAP)

lesions, 99, 101Drawer test, 146, 148fDVD clips, 21

EElastic tissue, 7f, 8Electrical modalities, 168-169Elevation of the arm, 10, 92

contact relationships in, 92examination of, 141-143scapular position in, 95

Endurance, 172Erb’s point, 30, 31fEvaluation of the shoulder, 4-6. See also pain.

active compression test, 149, 151fapplied physical stress concepts, 130-131apprehension tests, 157arthroscopic techniques, 130, 149, 158of the capsular pattern, 106-107cervical spine screening, 24-26, 25t, 27fclunk test, 149, 150fcommon disorders of, 14-18, 161discogenic pain, 26drawer test, 146, 148festablishing a therapeutic relationship, 132-133goals of, 131-132imaging techniques, 130, 149, 158impingement tests, 112-114influence of body types, 4-6joint laxity screening, 6Kibler lateral scapular slide test, 120-121,

149, 150fload and shift test, 146, 148fmedical history, 132-140

aggravating factors, 138assessment of functional limitations, 139-140location of pain, 137-138mechanism of injury, 136medical conditions, 133of nociceptive mechanics, 138pain behavior and intensity, 138-139patient’s description of the problem, 140predisposing factors, 133-136

Neer impingement test, 134t, 154nerve root screening, 24, 25toccupational and sports activities, 133-136pathomechanical vs. pathoanatomical approaches,

129-131physical examination, 140-158

assessment of active motion, 141-145assessment of connective tissue laxity, 155impingement tests, 153-155joint play and stability, 132, 156-158neural conduction problems, 153observation and inspection, 140-141

INDEX 225


226 INDEX

Evaluation of the shoulder (Continued )palpation, 146-150passive motion and provocation, 145-146physiological motion testing, 155-156radiography and arthroscopy, 158resisted tests, 150-153sequence of, 140t, 141t, 146t, 155tstanding position, 140t, 141

questionnaires, 133t, 139-140relocation test, 157Speed’s test, 152f, 153sulcus test, 146, 147fsyndrome classification, 131-132transient numbness/paresthesias, 136-137

Examination of the shoulderreferred pain, 27t

Exercises, 173-213crossing relationships, 173-174dumbbell curls, 204functional strengthening, 190-204pull-downs and pull-ups, 187-189pushing, 205-210rowing, 183-186seated resistance and stabilization, 181-183sensorimotor integration and speed, 211-213strengthening from the prone position, 175-180

External impingement, 153-154External obliques, 62-63, 86, 86f

FFall injuries, 136Fascial coverings, 66-67Forces of muscular contraction, 48, 50, 162Fractures, 161Frequency of shoulder injuries

aging and normal degenerative changes, 2-3from occupational causes, 1-2from sports activities, 2-3

Frozen shoulder, 106-107age factors, 134aggravating factors in, 138inflammatory processes in, 155-156treatment of, 122

GGlenohumeral joint, 85

adhesive capsulitis of, 106-107arthritis of, 18, 19f, 19tcapsular pattern of, 155-156capsulitis of, 137close- and loose-packing of, 96

Glenohumeral joint (Continued )connective tissue structures of, 97-106

capsular ligaments, 104-107glenoid labrum, 97-102joint capsule and synovial membrane, 102-104

counterbalancing muscles of, 80tcrossing relationships in, 77fdislocations of, 2in elevation of the arm, 10, 92enervation of, 33, 34examination of, 144-145, 155-158external rotation of, 10glenoid cavity, 93-97glenoid fossa, 93-97, 99-102head of the humerus, 92-93infraspinatus, 67instability of, 16-17, 98-99tlabral defects of, 99-102layers of conjoint tendon of, 69-70, 72flong head of the biceps, 84-85mechanics of, 93-96mobilization of, 4, 92neuroanatomy of, 41-45passive joint mobilization of, 95proprioception of, 41, 43rehabilitation of, 13resistance exercises for, 95rotation of, 144-145scapula, 93shear and compression of suprahumeral tissues

of, 76fstability of, 41, 43-44, 47, 50, 73-75, 85, 97-98suprahumeral dome, 93treatment of, 169, 171f

Glenohumeral joint capsule, 7t, 102-107adhesive capsulitis, 106-107anatomy and mechanics of, 3-4Bankart lesion of, 99, 100-101fexamination of, 143, 144f, 149-150, 156-158hypermobility of, 156-158instability of, 136, 137f, 138laxity of, 6ligaments of, 104-107link with rotator cuff, 3-4obligate translation of, 107restriction of, 143, 144frotator interval, 106suprahumeral-subacromial interface, 107-108

Glenoid fossa, 7t, 93-97, 96fcartilage covering of, 93contact relationships of, 92, 96


Glenoid fossa (Continued )defects of, 99-102possible orientations of, 93

Glenoid labrum, 7t, 97-98examination of, 147, 149, 150finjuries to, 85, 97lesions of, 97-102, 161sealing phenomenon of, 97-98

Gluteus maximus, 50t, 52-53Glycosaminoglycans, 8, 9f

HHanger muscles of the shoulder, 74-75, 78fHead of the humerus. See humeral head.Healing. See treatment of mechanical shoulder

injuries.Hematopoietic tissue, 7fHilton’s law, 41History. See medical history.Humeral head, 7t, 92-93, 94f

cartilage covering of, 93, 94fcontact relationship to the glenoid fossa, 92, 96examination of, 141ossification centers of, 93, 95f

Humerus, 7t. See also subluxation of the humeralhead.

action of the latissimus dorsi on, 52action of the teres major on, 54anatomy of, 16anterior dislocations of, 34elevation of, 58examination of upward rotation, 77-78fractures of, 16muscular attachment to the scapula of, 64-75suprahumeral-subacromial interface, 107-114treatment of, 77-78upward rotation of, 77-78

Hypertrophy of muscles, 48

IImaging and arthroscopic techniques, 130, 149, 158Immobilization of the shoulder girdle, 3Impingement syndromes

acromioclavicular joint in, 114association with subluxation, 218association with swimming, 134biceps tendon in, 70clinical examples of, 214-216decreased serratus anterior activity in, 95examination of, 112-114, 143, 144f, 152f, 153-155exercises for, 58

Impingement syndromes (Continued )external, 153-154internal, 114, 154-155in kyphosis, 135-136limitations in rotation with, 103-104Neer Classification Scheme for Shoulder

Impingement, 134tpostsurgical rehabilitation of, 216-218reverse capsular pattern in, 156from rotator cuff tears, 70scapular asymmetry in, 121scapular mechanics in, 64, 121strengthening exercises for the trapezius, 64

Inclined bench press, 205Industrial disabilities. See occupational disorders.Inferior glenohumeral ligament, 105-106Infraspinatus, 25t, 31, 62f, 65-67, 71f, 72f, 75f

conjoint tendon of, 49counterbalancing role of, 4, 78fcrossing relationships of, 50texamination of, 149-150fascial covering of, 4, 66-67, 68fresistance exercises for, 67role of, 67, 103in rotator cuff tears, 74ftendons of, 49three heads of, 65-66, 67ftreatment of, 67, 216weakness of, 33-34

Instability of the shoulder, 98-99t, 132, 161age factors in, 133anterior aspect of the glenohumeral joint capsule

in, 136, 137f, 138atraumatic etiology with multidirectional

instability pattern (AMBRI), 137-138Bankart lesions, 99, 100-101f, 137clinical examples of, 218-219examination of, 98-99t, 146, 147f, 156-158impingement syndromes in, 153-154sulcus test for, 146, 147fsuperior labrum anterior to posterior (SLAP)

lesions, 85, 99, 101-102surgical management of, 219-221treatment of, 172-173unidirectional, 138

Intent of treatment, 163-165, 221maintenance of function, 161-162, 164optimization of the healing environment, 164prevention of further injury, 164-165restoration of anatomical relationships, 164

Intercostals, 76, 121

INDEX 227


Internal impingement, 114, 154-155Internal oblique, 86Intervertebral discs, 24Iontophoresis, 214

JJoint capsules of the shoulder complex, 7fJoint kinematics, alterations of, 3Joint laxity screening, 6Joint mobilization, 4, 92

passive, 95, 122of the scapula, 122, 123ftechniques for, 169, 171f

Joints of the shoulder complex, 7f. See also names ofspecific joints, e.g. glenohumeral joint.

KKibler lateral scapular slide test, 120-121, 149, 150f

LLabral defects, 99-102

Bankart lesion, 99, 100-101fsuperior labrum anterior to posterior (SLAP)

lesions, 99, 101-102Latissimus dorsi, 25t, 51-53

action on the humerus of, 52attachments to the serratus anterior of, 51-52, 62counterbalancing role of, 78fcrossing relationships of, 50t, 52-53scapulothoracic interface and, 123strengthening exercises for, 55ttendons of, 49

Latissimus dorsi pull-down, narrow grip, 188Latissimus dorsi pull-down, wide grip, 187Laxity of the glenohumeral joint capsule

in internal impingement syndromes, 154-155screening of, 6

Levator scapula, 25t, 59-60mechanics of, 59pain and tenderness of, 59-60role of, 59-60, 124fscapulothoracic interface and, 122serape effect and, 63-64size of, 59strengthening exercises for, 62ttendons of, 49treatment of, 62t, 216

Ligaments of the shoulder complex, 7t. See alsonames of specific ligaments, e.g., coracoacro-mial ligament.

Load and shift test, 146, 148f

Loading variables, 4-6barrier positions, 162-163biomechanics of, 12-13, 13f

Long head of the biceps, 70, 84-85compression of, 85examination of, 149-150, 152f, 153exercises for, 85flattening of the tendon, 111-112function of, 84-85stability of the glenohumeral joint, 85superior labrum anterior to posterior (SLAP)

lesions, 99, 101, 152f, 153tendonitis of, 153tendon of, 17, 18f

Long head of the triceps, 64, 72-75crossing relationships of, 73-74, 77ffunctions of, 73-75subluxation of the humeral head, 74

Long thoracic nerveexamination of, 33-34, 35f, 36finjuries to, 33-34

Loose connective tissue, 7fLumbar spine, 86f

MMacrotrauma, 1Manual techniques, 169, 171Mechanical diagnosis, 129-130Mechanical function of the shoulder, 4-6. See also

neurophysiology of the shoulder.compression in, 49crossing and overlapping of muscles in, 50forces of muscle contraction in, 50shear forces in, 49-50torque in, 49

Mechanical loads of the shoulder jointposterior shear force, 5f

Mechanoreceptors, 7tMedial acromion, 7tMedical history, 132-140

aggravating factors, 138assessment of functional limitations, 139-140location of pain, 137-138mechanism of injury, 136medical conditions, 133of nociceptive mechanics, 138pain behavior and intensity, 138-139patient’s description of the problem, 140predisposing factors, 133-134, 133-136

Medication use, 168Microtrauma, cumulative, 1-2

228 INDEX


Middle glenohumeral ligament, 105Mobilization of the shoulder. See joint mobilization.Modulation of resting state of muscle contractions,

169Motion exercises, 4Mucous tissue, 7fMuscle tissue

anatomy and mechanics of, 3-4effects of immobilization on, 3of the infraspinatus fascia, 4role in joint articulations, 3-4strength training of, 4structure of, 48-50

Musculature of the shoulder, 47-88. See alsomechanical function of the shoulder.

abdominal musculature, 86-87anterior region, 80-85

anterior deltoid, 80, 83biceps brachii, 80coracobrachialis, 80, 83-84long head of the biceps, 84-85pectoralis major, 80, 81-83pectoralis minor, 80, 83short head of the biceps, 84sternocleidomastoid, 80-81

characteristics of function of, 48tcrossing and overlapping of muscles, 50, 73-75posterior scapular layer, 64-75

conjoint tendons of the rotator cuff, 70, 72fdeltoid, 25t, 64, 71-73, 74, 75fexercises for, 74thanger muscles, 74-75, 78finfraspinatus, 62f, 65-67, 68f, 70, 71f, 72flong head of the triceps, 64, 73-75supraspinatus, 25t, 62f, 64, 68-71, 72fteres minor, 25t, 62f, 64, 67-68, 69f, 70, 71f, 72f

scapular layerlevator scapula, 58-60, 64rhomboids, major and minor, 58-59, 60-61,

62f, 64serratus anterior, 58-59, 61-64

serape effect, 63-64size of, 48subscapular region, 76-80

exercises for, 80tserratus anterior, 76-78subscapularis, 78-80, 79f

superficial layerlatissimus dorsi, 51-53, 63teres major, 51, 53-54trapezius, 51, 55-58, 61

tissue disorders of, 161Musculocutaneous nerve, 41, 42f

NNeck disorders, passive mobilization for, 122Neer Classification Scheme for Shoulder

Impingement, 134t, 154Nerve root disorders, 21

neuroanatomy of, 25tscreening of, 24-25, 25tsymptoms of, 24-25

Nerve root screen, 24, 25tNerve tissue disorders, 161Neuroanatomy of the shoulder, 21-45

articular neurology, 41-45brachial plexus, 26, 28-30, 31f, 32fcervical spine, 22-26peripheral nerves, 28, 30, 31-35

axillary nerve, 34-35, 37tlong thoracic nerve, 33-34, 35f, 36fspinal accessory nerve, 35, 38f, 39fsuprascapular nerve, 31-33, 34f

thoracic spine, 22-24Neurological thoracic outlet syndrome, 37-38Neuromuscular control, development of

plyometric exercises, 44-45proprioceptive neuromuscular facilitation, 44, 54,

55tNeurophysiology of the shoulder

brachial plexus, 30-31joint stability, 41, 43-44proprioception, 41, 43stinger injuries, 28, 29fthoracic outlet syndrome, 35-38, 39f, 40f

Neurovascular compression syndromes, 161Nociceptors, 21, 138Nonsteroidal anti-inflammatory drugs (NSAIDS), 168NSAIDS. See nonsteroidal anti-inflammatory drugs

(NSAIDS).Numbness/paresthesias, 136-137

OObjectives of treatment, 166-173

application of controlled forces, 161-162, 169-171biomechanical counseling, 167-168enhancement of neuromuscular health, 161,

172-173enhancement of performance, 172-173pain modulation, 161, 168-169patient education, 167-168promotion of analgesia, 168-169

INDEX 229


Obligate translation of the glenohumeral jointcapsule, 107

Occupational disorders, 1-2, 6biomechanics of repetitive loading, 12-13, 13fexamination of, 133-136incidence of, 1overuse syndromes, 135-136repetitive strain syndrome, 161risk of, 2symptoms of, 1work environments associated with, 1-2

Osacromiale, 93Outcome predictions, 167

PPacinian nerve endings, 41Pain, 136-138, 168

barrier positions, 162-163bilateral, 133Blazina classification of pain, 139tof cervical nerve root etiology, 137, 138tdiscogenic, 26examination of, 142-143, 144f, 146instability and, 137-138location of, 137-138medications for, 168modulation of, during treatment, 168-169from nerve root irritation, 24-25patient’s interpretations of, 138-139referred, 25-26, 27t, 129, 133, 137, 163role of, in treatment, 165-166sleep and, 138-139sources of, 129-130tolerance of, 168

Passive joint mobilization, 95, 122. See also jointmobilization.

Patient education, 161, 163, 167-168Pectoralis major, 25t, 75f, 81-83, 87

counterbalancing role of, 78fcrossing relationships of, 74-75, 82f, 83hanger function of, 78fscapulothoracic interface, 123tendons of, 49

Pectoralis minor, 25t, 122Pelvic floor muscles, 86fPeripheral nerve injuries, 21, 137

of the axillary nerve, 34-35, 37tof the brachial plexus, 31-35of the long thoracic nerve, 33-34, 35f, 36fof the spinal accessory nerve, 35, 38f, 39fof the suprascapular nerve, 31-33, 34f

Phonophoresis, 214Physical examination of the shoulder, 140-158. See

also evaluation of the shoulder.assessment of active motion, 141-145assessment of connective tissue laxity, 155impingement tests, 153-155joint play and stability, 132, 156-158neural conduction problems, 153observation and inspection, 140-141palpation, 146-150passive motion and provocation, 145-146physiological motion testing, 155-156radiography and arthroscopy, 158resisted tests, 150-153sequence of, 140t, 141t, 146t, 155tstanding position, 140t, 141

Plyometric exercises, 44-45, 219PNF. See proprioceptive neuromuscular facilitation

(PNF).Posterior humeral artery, 77fPosterior scapular muscles, 64-75

conjoint tendons of the rotator cuff, 70, 72fdeltoid, 25t, 64, 71-73, 74, 75fexercises for, 74thanger muscles, 74-75, 78finfraspinatus, 62f, 65-67, 71f, 72flong head of the triceps, 64, 73-75supraspinatus, 25t, 62f, 64, 68-71, 71f, 72fteres minor, 25t, 62f, 64, 67-68, 69f, 70,

71f, 72fPostsurgical rehabilitation, 169, 216-218, 220-221Postural mechanics

antigravity forces and, 59-60, 64, 65fof humeral function, 60, 65fkyphosis and, 135-136long thoracic nerve injury and, 34serape effect and, 63-64sternocleidomastoid alignment and, 81thoracic outlet syndrome and, 37

Power, 172Prone lying forward humeral elevation exercise, 177Prone lying humeral abduction exercise, 176Prone lying humeral extension and scapular

retraction with elbow flexion exercise, 175Prone lying humeral extension with external

rotation exercise, 180Prone lying humeral extension with internal

rotation exercise, 179Prone lying resisted scaption exercise, 178Prone lying scapular retraction exercise, 175Proprioception of the shoulder, 41, 43

230 INDEX


Proprioceptive neuromuscular facilitation (PNF), 44,54, 55t

Proteoglycan, 8-10, 9fPulling, scapular stability in, 123, 124fPull-up, gravity assisted, 189Pushing, scapular protraction in, 77-78Pushing exercises, 77-78Push-ups, 206

posterior shear force in, 4, 5fscapular position in, 95

QQuestionnaire for patient history, 133t

RRange of a muscular contraction, 48Rectus abdominis, 86-87, 86fReferred pain, 163

in capsulitis, 137from the cervical spine, 25-26, 27tfrom visceral structures, 26, 129, 133

Reflex responses, generation of, 43Rehabilitation. See treatment of mechanical

shoulder injuries.Relocation test, 157Repetitive loading of connective tissue, 12-13, 13fRepetitive strain syndrome, 161. See also

occupational disorders.Resisted exercise, 172-173Resisted functional training, one-handed diagonal

with full movement, 213Resisted functional training, one-handed diagonal

with isolated movement, 212Resisted functional training, two-handed straight

on, 211Resting tension of the shoulder, 43-44Reticulin fiber, 8Rheumatoid arthritis, 102-103Rheumatoid disease, 133Rhomboids, major and minor, 25t, 58-59, 60-61, 62f

crossing relationships of, 50tscapulothoracic interface, 122serape effect, 64stability of the scapula, 124fstrengthening exercises for, 62ttreatment of, 216

Ribs, 7tRole of pain, 165-166Rotation of the shoulder, 144-145

external, 10limitations of, 103-104

Rotator cuffarticular surface of, 108bursal surface of, 108conjoint tendon of, 70, 72fcontact relationships of, 92examination of, 151-153interval, 17, 18fjoint capsule of, 3-4, 103proprioception, 41, 43strengthening of, 71suprahumeral-subacromial interface of, 107-110

Rotator cuff injuries, 2-3, 17, 17fage factors, 70, 71, 134aggravating factors in, 138compromise of the subacromial space in, 112tdegenerative processes of, 108-110effects of repetitive stress on, 13-14external impingement and, 153-154impingement tests for, 112-114location of, 73flong head of the biceps tendon in, 85osacromiale, 93postsurgical rehabilitation of, 216-218resulting in impingement syndrome, 70scapular pain in, 59-60shear forces, 50size of, 74ftears, 70, 71, 73f, 74f, 161treatments for, 13, 74t, 122, 215-216

Ruff ini nerve endings, 41

SScapula, 7t, 64, 93, 96f. See also acromion; posterior

scapular muscles.bursa of, 76compression of, 51-52elevation of, 95examination of, 143-145glenoid cavity of, 93-97in impingement syndromes, 64mobility of, 66fmotions of, 121-123musculature of

levator scapula, 59-60, 64rhomboids, major and minor, 58-59, 60-61,

62f, 64serratus anterior, 58-59, 61-64

ossification centers in, 93position of, in push-ups, 95role of acromioclavicular joint movement on, 58role of sternoclavicular joint movement on, 58

INDEX 231


Scapula (Continued )role of the trapezius muscle on, 55-58serape effect, 63-64, 77snapping scapula syndrome, 121stabilization of, 123, 124fsubluxation or dislocation of, 34ftendinous tissue attachments of, 62ftreatments of, 95, 122, 123f, 170f, 216“winging,” 34, 37f

Scapular circumflex artery, 77fScapulohumeral rhythm, 64, 122Scapulothoracic interface, 119-124

bursa of, 121joint stability of, 47Kibler lateral slide test of, 120-121mobilization of, 123ftreatments of, 170f, 216

Seated diagonal low row, bilateral, 204Seated dumbbell curls, 204Seated forward elevation and upward rotation of

the scapula exercise, 182Seated humeral forward elevation exercise, 181Seated row, high range with no spinal motion, 184Seated row, high range with trunk flexed, 186Seated row, midrange with trunk flexed, 185Seated scapular elevation and retraction with

dumbbells, 181Seated scapular elevation and retraction with

humeral abduction and external rotation usingdumbbells, 183

Serape effect, 63-64, 77Serratus anterior, 25t, 58-59, 61-64, 76-78, 80t, 85

attachments to the latissimus dorsi, 51-52, 62crossing relationships of, 50t, 52-53in impingement syndromes, 95in pushing exercises, 77-78scapulothoracic interface of, 121, 122serape effect, 63-64, 77stability of the scapula and, 124ftreatments of, 62t, 216upward rotation of, 77-78

Serratus posterior, 121Serratus posterior superior, 76Shear forces, 49-50, 130-131, 146Short head of the biceps, 72, 84

crossing relationships of, 73-74, 77fsuprahumeral-subacromial interface and, 107-108tendon of, 17

Shoulder Pain and Disability Index (SPADI), 139-140

Simple Shoulder Test (SST), 139

Single armed dumbbell row, 183SLAP. See superior labrum anterior to posterior

(SLAP) lesions.Sleep and pain, 138-139Small subclavian nerve, 41, 42fSnapping scapula syndrome, 121Soft tissue injuries. See connective (soft) tissue

injuries.Soft tissue techniques, 168fSpecialized connective tissue, 6-8, 7f

biomechanics of, 10-14disorders of, 10-14

Speed’s test, 152f, 153Spinal accessory nerve (cranial nerve XI), 35, 38f,

39fSplints, 171Sports injuries, 2, 6

Bankart lesion in, 99, 100-101fin contact sports, 134, 136, 137fexamination of, 133-136injuries to the brachial plexus in, 28, 29finternal impingements in, 114repetitive loading in, 12-13rotator cuff tendon failure in, 13-14stinger injuries in, 28, 29ffrom stretching, 34subluxation, 134superior labrum anterior to posterior (SLAP)

lesions, 99, 101-102from swimming, 134tendonitis, 152f, 153from tennis, 134from throwing, 67, 85, 99, 100-101f, 101, 134,

135tfrom weight lifting, 134-135

Stability of the shoulder, 41, 43-44, 47, 50, 132. Seealso instability of the shoulder.

acromioclavicular joint, 55examination of, 156-158role of the glenoid labrum, 97-98role of the joint capsule, 103

Standing diagonal low row, bilateral, 203Standing high row, low range, 191Standing high row, midrange, 190Standing humeral abduction, external rotation, 202Standing low row, high range, 199Standing low row, midrange, 200Standing low row, scapular elevation, 201Standing mid-row, high range, 194Standing mid-row, low range, 195Standing mid-row, midrange, 193

232 INDEX


Standing one-armed punch, 198Standing one-armed diagonal high row with

external rotation, 193Standing one-armed diagonal low row, 202Standing one-armed diagonal mid-row with

increased trunk motion, 197Standing one-armed mid-row, midrange with

external rotation, 196Standing two-handed diagonal high row, 192Sternoclavicular disc, 7tSternoclavicular joint, 41, 123-124, 125f

capsular ligament of, 124, 126fcapsule of, 7texamination of, 157-158injuries to, 15-16, 15frole of, 58stability of, 124, 126f

Sternoclavicular ligament, 81fSternocleidomastoid, 80-81Sternum, 7tSteroids, 168Stimulation of fluid dynamics, 169Stinger injuries to the brachial plexus, 28, 29fStrength training, 4, 172-173Stress and strain on connective tissue, 10-12Stretching of connective tissue, 10Structure of muscles. See muscle tissue.Subacromial bursa, 149-150Subacromial debridement, rehabilitation of, 216-218Subacromial-suprahumeral interface, 107-114

clinical examples of, 214-216compromise of the subacromial space, 112t

Subclavian nerve, 41, 42fSubclavian vasculature, thoracic outlet syndrome in,

36, 39fSubclavian veins and thoracic outlet syndrome, 39fSubclavius, 81, 81fSubluxation of the humeral head, 4, 6, 99

association with impingement syndrome, 218clinical examples of, 218-219from falls, 136internal impingement syndromes, 154-155loss of triceps muscle function and, 74passive restraints to, 66superior labrum anterior to posterior (SLAP)

lesions, 99, 101Subscapularis, 25t, 70, 72f, 75f, 78-80

counterbalancing role of, 79-80crossing relationships of, 50t, 73, 77fin rotator cuff tears, 74fscapulothoracic interface, 121

Subscapularis (Continued )support of the joint capsule, 103treatment of, 215

Subscapular musculature, 76-80exercises for, 80tserratus anterior, 76-78subscapularis, 77-78, 78-80

Subscapular nerve, 41, 42fSulcus test, 146, 147fSuperficial musculature

elevation of the humerus and, 58latissimus dorsi, 51-53strengthening exercises for, 55tteres major, 51, 53-54trapezius, 51, 55-58treatment of, 54, 55t

Superior glenohumeral ligament, 105Superior labrum anterior to posterior (SLAP)

lesions, 85, 99, 101-102, 152f, 153Supine flys, 205Supine lying resisted humeral extension, 207Supine lying resisted humeral extension, combined,

208Supine lying resisted push, 210Supine lying scapular protraction, isolated, 209Supraclavicular nerve, 41, 42fSupraclavicular region, 28Suprahumeral space, 93, 149-150Suprahumeral-subacromial interface, 107-114Suprascapular artery, 31, 33fSuprascapular nerve, 31-33, 41, 42f

examination of, 32-33injuries to, 32-33, 34f

Supraspinatus, 25t, 31, 62f, 64, 68-71, 72fconjoint tendon of, 49examination of, 149-150hanger function of, 78frole of, 67-69, 78f, 103in rotator cuff injuries, 74f, 110strengthening of, 70treatment of, 215weakness of, 33-34

Surgical treatmentsarthroscopic debridements, 217inferior capsular shift procedure, 137for instability, 219-221open repairs, 217-218postsurgical rehabilitation of, 169, 216-218, 220-

221variability of, 162, 216

Swimming, 134

INDEX 233


Synchronous relationships, scapulohumeral rhythmin, 64, 122

Synovial lining, 7t, 102-104

TTaping, 171Tendonitis, 161Tendon tissue, 70Tension, examination of, 130-131, 146Teres major, 51, 53-54

action on the humerus of, 54counterbalancing role of, 78fcrossing relationships of, 50t, 77fexamination of, 54intersection with the long head of the triceps, 73strengthening exercises for, 55t

Teres minor, 25t, 62f, 64, 67-68, 69f, 70, 71f, 75f,77f

conjoint tendon of, 49counterbalancing role of, 78fintersection with the long head of the triceps, 73support of the joint capsule, 103treatment of, 216

Therapeutic relationships with patients, 132-133Thermal modalities, 168-169Thoracic outlet syndrome, 35-38, 39f, 40f

anatomy of, 36-37, 40fexamination of, 37-38, 40ftreatment of, 38

Thoracic spine, 22-24Thorax. See scapulothoracic interface.Torque, 49Total joint arthroplasty, 161Transverse humeral ligament, 7tTransverse scapular ligament, 7tTransversus abdominis, 86-87Trapezius, 25t, 51, 55-58, 61

crossing relationships of, 50tin impingement syndromes, 58, 64scapulothoracic interface of, 122stability of the scapula and, 124fstrengthening exercises for, 55t, 58treatment of, 58, 216

Trapezius aponeurosis, 55Traumatic Unilateral Bankart Surgery (TUBS), 99,

137Treatment of mechanical shoulder injuries, 4. See

also clinical examples; surgical treatments.barrier positions in, 162-163closed kinetic chain for, 95controlled loading in, 12-13, 162

Treatment of mechanical shoulder injuries (Continued )development of neuromuscular control in, 44electrical modalities in, 168-169establishing joint stability in, 43-44exercises, 173-213

crossing relationships, 173-174dumbbell curls, 204functional strengthening, 190-204pull-downs and pull-ups, 187-189pushing, 205-210rowing, 183-186seated resistance and stabilization, 172-173,

181-183sensorimotor integration and speed, 211-213strengthening from the prone position, 175-180

increase of afferent input in, 169intent of, 163-165, 221

maintenance of function, 161-162, 164optimization of the healing environment, 164prevention of further injury, 164-165restoration of anatomical relationships, 164

iontophoresis in, 214joint mobilization techniques in, 169, 171fmanual techniques in, 169, 171medication use in, 168modification of connective tissue in, 169modulation of pain in, 168-169modulation of resting state of muscle contractions

in, 169objectives of, 166-173

application of controlled forces, 161-162, 169-171

biomechanical counseling, 167-168enhancement of neuromuscular health, 161,

172-173enhancement of performance, 172-173pain modulation, 161, 168-169patient education, 167-168promotion of analgesia, 168-169

outcome predictions in, 167patient education, 163, 167-168patient education in, 161phonophoresis in, 214plyometric exercises in, 44-45, 219postsurgical rehabilitation in, 169, 216-218, 220-

221postural components of, 60proprioceptive neuromuscular facilitation in, 44,

54, 55tpushing exercises in, 77-78role of pain in, 165-166

234 INDEX


Treatment of mechanical shoulder injuries (Continued )soft tissue techniques for, 169, 170fsplints for, 171stimulation of fluid dynamics in, 169strengthening in, 172-173taping in, 171thermal modalities in, 168-169weight training in, 172-173

Triceps, 25t. See also long head of the triceps.crossing relationships of, 50thanger function of, 78f

Tropocollagen, 8, 9fTUBS. See Traumatic Unilateral Bankart Surgery

(TUBS).

UUpward rotation of the humerus, treatment of,

77-78

Upward rotation of the scapula, treatment of, 209US Bureau of Labor, incidence of occupational

cervicobrachial disorders, 1

VVascular thoracic outlet syndrome, 37-38Visceral structures, 26, 129, 133

WWeight training, 172-173Wilk, K. E., 44Winging scapula, 34, 37fWork-related injuries. See occupational disorders.

INDEX 235


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