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Biomechanics of
Human Upper
ExtremityPicture retrieved from http://catalog.nucleusinc.com/enlargeexhibit.php?ID=797
ENT 214 Biomechanics
Picture retrieved from
http://thestar.com.my/archives/2006/12/9/sports/Sazali.jpg
Retrieved from
http://en.wikipedia.org/wiki/Image:Human_arm_bones_diagram.svg
Sternum
Manubrium
Sternoclavicular jointAcromioclavicular jointCoracoclavicular jointGlenohumeral jointScapulothoracic joint
Structure of the Shoulder
Structure of the Shoulder
Sternoclavicular joint: modified ball and socket joint between the proximal clavicle and the manubrium of the sternum
Interclavicular ligament
Clavicle
Sternoclavicular ligament
Costoclavicular ligament
Sternum
Clavicle
Articular disk
Costal cartilage (1st rib)
Structure of the Shoulder
Acromioclavicular joint: irregular joint between the acromion process of the scapula and the distal clavicle
Coracoclavicular ligament
Coracoclavicular ligament
Anterior view Posterior view
Clavicle
Verterbal border
Acromioclavicular joint
Acromion process
Coracoacromial ligament
Coracoid process
Glenoid fossa
Axillary border
Inferior angle
Clavicle
Scapular spine
Vertebral border
Inferior angle
Structure of the Shoulder
Coracoclavicular joint: syndesmosis with the coracoid process of the scapula bound to the inferior clavicle by the coracoclavicular ligament
Coracoclavicular ligament
Coracoclavicular ligament
Anterior view Posterior view
Clavicle
Verterbal border
Acromioclavicular joint
Acromion process
Coracoacromial ligament
Coracoid process
Glenoid fossa
Axillary border
Inferior angle
Clavicle
Scapular spine
Vertebral border
Inferior angle
Structure of the Shoulder
Glenohumeral joint: ball and socket joint in which the head of the humerus articulates with the glenoid fossa of the scapula
Acromion process
Coracohumeral ligament
Long head of biceps
Humerus
Coracoid process
Articular capsule
Scapula
Structure of the Shoulder
What is the scapulothoracic joint?
articulation between the anterior scapula and the thoracic wall
Bursae
A small fluid-filled sac located between movable parts of the body especially at joints
Reduce friction between layers of collagenous tissue
Movements of the Shoulder Complex
scapulohumeral rhythm: a regular pattern of scapular rotation that accompanies and facilitates humeral abduction
First 30o humeral elevation, contribution of scapula only 1/5 of glenohumeral joint
Beyond 30o, scapula rotates 1o for every 2o of humerus movement
First 90o of arm elevation, clavicle elevated 35o to 45o of motion at sternoclavicular joint.
Movements of the Shoulder Complex
Movements of the Shoulder Complex
What muscles contribute to flexion at the glenohumeral joint?
anterior deltoid clavicular pectoralis major assisted by:
coracobrachialis short head of biceps brachii
Retrieved from
http://upload.wikimedia.org/wikipedia/commons/d/de/Gray410.png
Movements of the Shoulder Complex
What muscles contribute to extension at the glenohumeral joint? sternal pectoralis major latissimus dorsi teres major assisted by:
long head of triceps brachii
Retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/d/d6/Deltoideus_posterior.PNG
Movements of the Shoulder Complex
What muscles contribute to abduction at the glenohumeral joint?
middle deltoid supraspinatus
Retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/8/8f/Gray412.png
Movements of the Shoulder Complex
What muscles contribute to adduction at the glenohumeral joint? latissimus dorsi teres major sternal pectoralis major assisted by:
short head of biceps brachii long head of triceps brachii
Movements of the Shoulder Complex
What muscles contribute to medial rotation of the humerus?
subscapularis teres major assisted by:
pectoralis major anterior deltoid latissimus dorsi short head of biceps brachii
Retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/f/f2/Gray411.png
Movements of the Shoulder Complex
What muscles contribute to lateral rotation of the humerus?
• infraspinatus• teres minor• assisted by:
• posterior deltoid
Movements of the Shoulder Complex
What muscles contribute to horizontal adduction of the humerus?
• pectoralis major• anterior deltoid• coracobrachialis• assisted by:
• short head of biceps brachii
Movements of the Shoulder Complex
What muscles contribute to horizontal abduction of the humerus?
infraspinatus middle and posterior deltoid teres minor assisted by:
teres major latissimus dorsi
Torque at shoulder
Torque created by weight of arm is the product of arm weight and perpendicular distance between arm’s COG and the shoulder
Torque at shoulder
Sample Problem 1
If the weight of the arm is 33 N, moment arm for the total arm segment is 30 cm, moment arm for deltoid muscle (Fm) is 3 cm.
How much force must be supplied by deltoid to maintain the arm in this position?
What is the magnitude of the joint reaction force (R)?
wt
Common Injuries of Shoulder
Dislocation Rotator Cuff Damage
Rotator cuff - anatomical term given to the group of muscles and their tendons that act to stabilize the shoulder
Example – supraspinatus, infraspinatus, teres minor, subscapularis muscles
Rotational Damage
Humeroulnar Joint
Retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/9/97/Gray329.png
Structure of the Elbow
What is the humeroulnar joint? hinge joint in which the humeral trochlea articulates with the trochlear fossa of the ulna
considered to be the elbow joint
Structure of the Elbow
What is the humeroradial joint?
gliding joint in which the capitellum of the humerus articulates with the proximal end of the radius
Structure of the Elbow
What are the radioulnar joints?
the proximal and distal radioulnar joints are pivot joints
the middle radioulnar joint is a syndesmosis
Movements at the Elbow
What muscles contribute to flexion at the elbow?
brachialis
biceps brachii
brachioradialis
Movements at the Elbow
What muscles contribute to extension at the elbow?
triceps brachii
assisted by:
anconeus
Retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/7/79/Musculusanconeus2.png
biceps
fore
force?
be
Common Injuries of Elbow
Sprains and dislocationEpicondylitis
Inflammation and sometimes microrupting of collagenous tissue at distal humerus
Wrist
Retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/6/66/Gray334.png
Structure of the Wrist
What are the radiocarpal joints? condyloid articulations between the radius and the three carpal bones
these joints comprise the wrist
Structure of the Wrist
What is the function of the retinacula at the wrist?
these fibrous bands of fascia form protective passageways through which tendons, nerves, and blood vessels pass
Movements at the Wrist
What muscles contribute to flexion at the wrist? flexor carpi radialis flexor carpi ulnaris palmaris longus assisted by:
flexor digitorum superficialis flexor digitorum profundus
Retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/5/5f/Gray418.png
Retrieved fromhttp://en.wikipedia.org/wiki/Image:Flexor-carpi-radialis.png
What muscles contribute to extension at the wrist? extensor carpi radialis longus extensor carpi radialis brevis extensor carpi ulnaris assisted by:
other wrist extensor muscles
Movements at the Wrist
F
I
N
G
E
RRetrieved fromhttp://upload.wikimedia.org/wikipedia/commons/f/f7/X-ray_boy_hand.jpg
Structure of the Hand Joints
What are the carpometacarpal joints?
the carpometacarpal joint of the thumb is a saddle joint
the other carpometacarpal joints are gliding joints
What are the intermetacarpal joints?
irregular joints between the metacarpals that share joint capsules with the carpometacarpal joints
Structure of the Hand Joints
What are the metacarpophalangeal joints?
condyloid joints between the rounded distal heads of the metacarpals and the concave proximal ends of the phalanges these joints form the knuckles of the hand
Structure of the Hand Joints
What are the interphalangeal joints?
the proximal and distal interphalangeal joints of the fingers and the single interphalangeal joint of the thumb are all hinge joints
Structure of the Hand Joints
Movements of the Hand
What motions are permitted at metacarpophalangeal joints 2-5?
flexion extension abduction adduction circumduction
Movements of the Hand
What muscles are responsible for motions of the hand?
there are nine extrinsic muscles with attachments both proximal and distal to the wrist there are ten intrinsic muscles with both attachments distal to the wrist
Common Injuries of Wrist & Hand
Fracture - boxers Injury - golfers Carpal tunnel syndrome
Passageway between carpal bone and flexor retinaculum
Symptom : pain, numbness along median nerve, clumsiness of finger function, atrophy of muscle
Summary
1. Shoulder – Structure– Movement and muscle involve– Common injuries
2. Elbow
3. Wrist
4. Hand
5. Force initiated and torque - calculation