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2/11 © Blue Sky School of Professional Massage and Therapeutic Bodywork 1
MSAK101-II – Session 2 – Shoulder Muscles
BLUE SKY SCHOOL OF PROFESSIONAL MASSAGE AND
THERAPEUTIC BODYWORK
Musculoskeletal Anatomy & Kinesiology II
SHOULDER GIRDLE MUSCLES
MSAK101-II Session 2
LEARNING OBJECTIVES:
By the end of this session, the student will be expected to:
1. Apply all review material.
2. List and describe new structures.
3. For the muscles of the shoulder muscles:
a. Locate.
b. Identify attachments points.
c. Demonstrate fiber direction.
d. List actions.
e. Describe relationship or layering to other musculoskeletal structures.
f. Palpate.
1) POSTERIOR SHOULDER GIRDLE MUSCLES:
a) Trapezius
i) Upper Trapezius
(1) Origin: External occipital protuberance, Nuchal ligament.
(2) Insertion: Lateral third of clavicle, acromion process.
(3) Fiber Direction: Superior to inferior at an angle laterally.
(4) Actions:
(a) Elevation of scapula.
(b) Upward rotation of scapula
(c) Unilateral lateral flexion of neck
(d) Bilateral extension of head and neck.
2/11 © Blue Sky School of Professional Massage and Therapeutic Bodywork 2
MSAK101-II – Session 2 – Shoulder Muscles
ii) Middle Trapezius
(1) Origin: SP’s of T1-T5.
(2) Insertion: Medial border of the acromion process and
the spine of scapula.
(3) Fiber Direction: Medial to lateral.
(4) Action: Retraction of scapula.
iii) Lower Trapezius
(1) Origin: SP’s of T6-T12.
(2) Insertion: Root of the spine of scapula.
(3) Fiber Direction: Inferior to superior at a lateral angle.
(4) Actions:
(a) Depression and retraction of scapula
(b) Upward rotation of scapula.
b) Levator Scapulae
i) Origin: TP’s of C1-C4.
ii) Insertion: Vertebral border of scapula from the superior
angle to the root of the scapular spine.
iii) Fiber Direction: Superior to inferior at an angle laterally.
iv) Actions:
(1) Elevation of the scapula
(2) Downward rotation of scapula
(3) Lateral flexion of neck
(4) Extension of neck.
v) Notes / relationship to other musculoskeletal structures:
(1) At its scapular attachment, the Levator is deep
only to the Trapezius.
(2) At its TP attachments, Levator is deep to the
Splenius capitis and the SCM.
2/11 © Blue Sky School of Professional Massage and Therapeutic Bodywork 3
MSAK101-II – Session 2 – Shoulder Muscles
c) Rhomboids
i) Rhomboid Minor
(1) Origin: SP’s of C7-T1.
(2) Insertion: Root of the spine of scapula.
(3) Fiber Direction: Superior to inferior at
an angle laterally.
(4) Actions:
(a) Retraction of the scapula.
(b) Elevation of the scapula.
(c) Downward rotation of the scapula.
(5) Notes / relationship to other musculoskeletal structures:
(a) The rhomboids are deep to the Trapezius.
(b) Rhomboid minor is directly superior to Rhomboid major.
(c) Rhomboid minor is directly inferior to Levator’s attachment.
ii) Rhomboid Major
(1) Origin: SP’s of T2-T5.
(2) Insertion: Vertebral border of scapula from
root of the spine to the inferior angle.
(3) Fiber Direction: Superior to inferior at
an angle laterally.
(4) Actions:
(a) Retraction of the scapula.
(b) Elevation of the scapula.
(c) Downward rotation of scapula.
(5) Notes / relationship to other musculoskeletal structures:
(a) When the Rhomboids are weak, they can contribute
to a “rounded shoulder” type appearance because they
(b) are unable to oppose protraction and depression of the scapulae.
2/11 © Blue Sky School of Professional Massage and Therapeutic Bodywork 4
MSAK101-II – Session 2 – Shoulder Muscles
2) ANTERIOR SHOULDER GIRDLE MUSCLES:
a) Serratus Anterior
i) Origin: Outer surface of ribs 1-9.
ii) Insertion: Anterior surface of the vertebral border of scapula.
iii) Fiber Direction: Lateral to medial.
iv) Actions:
(1) Protraction of scapula.
(2) Upward rotation of scapula.
(3) Stabilizes scapula against the chest wall.
v) Notes / relationship to other musculoskeletal structures:
(1) Posteriorly, Serratus anterior lies deep to the scapula.
Anteriorly, it is deep to the Pectoralis major and minor.
(2) The lowest slips of costal attachments interdigitate with the external obliques.
(3) Serratus anterior lies anterior to Subscapularis.
b) Pectoralis Minor
i) Origin: Anterior ribs 3-5 near the
costal cartilages.
ii) Insertion: Coracoid process of the scapula.
iii) Fiber Direction: Inferior to superior at lateral angle.
iv) Actions:
(1) Protraction of the scapula.
(2) Depression of the scapula.
(3) Downward rotation of scapula.
v) Notes / relationship to other musculoskeletal structures:
(1) Pectoralis minor is deep to Pectoralis major.
(2) Deep to Pectoralis minor are Serratus anterior and the ribcage.
(3) Pectoralis minor is one of three muscles that attach to the coracoid process.
2/11 © Blue Sky School of Professional Massage and Therapeutic Bodywork 5
MSAK101-II – Session 2 – Shoulder Muscles
c) Subclavius
i) Origin: First rib at costal cartilage (costochondral)
junction.
ii) Insertion: Middle third of inferior shaft of clavicle.
iii) Fiber Direction: Medial to lateral.
iv) Actions:
(1) Depression of clavicle.
(2) Stabilizes clavicle by moving it medially
v) Notes / relationship to other musculoskeletal structures:
(1) Subclavius is deep to the Pectoralis major.
(2) Deep to Subclavius are the brachial plexus and the subclavian artery and vein.
3) SHOULDER MUSCLES:
a) Deltoid
i) Origin:
(1) Anterior – Lateral third of clavicle.
(2) Middle - Lateral acromion process.
(3) Posterior – Spine of scapula.
ii) Insertion: Deltoid tuberosity.
iii) Fiber Direction: Generally, medial to lateral.
iv) Actions: (All of glenohumeral joint)
(1) Anterior – Flexion, abduction, horizontal adduction,
internal rotation
(2) Middle – Abduction to 90 degrees.
(3) Posterior – Extension, abduction, horizontal abduction, external rotation.
v) Notes / relationship to other musculoskeletal structures:
(1) Deltoid is superficial gives the shoulder its characteristic shape.
b) Coracobrachialis
i) Origin: Coracoid process of scapula.
ii) Insertion: Medial middle third of shaft of humerus.
iii) Fiber Direction: Superior to inferior at an angle laterally.
2/11 © Blue Sky School of Professional Massage and Therapeutic Bodywork 6
MSAK101-II – Session 2 – Shoulder Muscles
iv) Actions: (All of glenohumeral joint)
(1) Flexion.
(2) Adduction.
v) Notes / relationship to other musculoskeletal structures:
(1) This is one of three muscles that attach to the coracoid
process of the scapula. The other two are the short
head of the Biceps and the Pectoralis minor.
c) Latissimus Dorsi
i) Origin: Thoracolumbar aponeurosis, SP’s of T7-12, Sacrum, Iliac crest, Ribs 9-12
ii) Insertion: Medial lip of the bicipital groove of humerus.
iii) Fiber Direction: Inferior to superior at lateral angle.
iv) Actions: (All of glenohumeral joint)
(1) Extension.
(2) Internal rotation.
(3) Adduction.
v) Notes / relationship to other musculoskeletal structures:
(1) Teres major and Latissimus dorsi both attach onto the
medial lip of the biciptial groove.
d) Teres Major
i) Origin: Lower third of lateral border of scapula
just superior to inferior angle.
ii) Insertion: Medial lip of the bicipital groove.
iii) Fiber Direction: Inferior to superior at a lateral angle.
iv) Actions: (All of glenohumeral joint)
(1) Extension.
(2) Internal rotation.
(3) Adduction.
v) Notes / relationship to other musculoskeletal structures:
(1) Teres major and the Latissimus dorsi both attach onto the medial lip of the bicipital groove.
(2) Teres major is sometimes referred to as “Lat’s little helper”
2/11 © Blue Sky School of Professional Massage and Therapeutic Bodywork 7
MSAK101-II – Session 2 – Shoulder Muscles
e) THE ROTATOR CUFF (SITS Group)
i) Supraspinatus
(1) Origin: Supraspinous fossa of scapula.
(2) Insertion: Superior portion of greater tubercle of humerus.
(3) Fiber Direction: Generally, medial to lateral.
(4) Actions:
(a) Abduction of glenohumeral joint.
(b) Maintains vertical traction of the head of humerus
helping to hold the head in the glenoid fossa.
(5) Notes / relationship to other musculoskeletal structures:
(a) “S” in “SITS”.
(b) The only rotator cuff muscle that does not contribute to rotation of arm.
(c) Supraspinatus is the most commonly injured of the rotator cuff musculature.
Infraspinatus
(6) Origin: Infraspinous fossa of scapula.
(7) Insertion: Posterior surface of greater tubercle of humerus.
(8) Fiber Direction: Medial to lateral at an angle superiorly.
(9) Actions: (All of glenohumeral joint)
(a) Extension.
(b) External rotation.
(c) Horizontal adduction.
(10) Notes / relationship to other musculoskeletal structures:
(a) “I” in “SITS”.
ii) Teres Minor
(1) Origin: Upper lateral border of scapula.
(2) Insertion: Inferior facet of greater tubercle of humerus.
(3) Fiber Direction: Medial to lateral at an angle superiorly.
(4) Actions: (All of glenohumeral joint)
(a) Extension
(b) External rotation
(c) Horizontal adduction.
(5) Notes / relationship to other musculoskeletal structures:
(a) “T” in “SITS”.
(b) On the scapula, the Teres minor attaches superiorly to Teres major.
2/11 © Blue Sky School of Professional Massage and Therapeutic Bodywork 8
MSAK101-II – Session 2 – Shoulder Muscles
iii) Subscapularis
(1) Origin: Entire anterior surface of the subscapular fossa.
(2) Insertion: Lesser tubercle of humerus.
(3) Fiber Direction: Medial to lateral.
(4) Action: (All of glenohumeral joint)
(a) Internal rotation.
(5) Notes / relationship to other musculoskeletal structures:
(a) The Second “S” in “SITS”.
(b) Subscapularis is deep to scapula and superficial to
Serratus Anterior and the ribcage.
(c) Only rotator cuff muscle to attach to lesser tubercle and to rotate the arm internally.
f) Pectoralis Major
i) Origin:
(1) Clavicular head – medial half of anterior clavicle.
(2) Sternal head – sternum and cartilages of ribs 1-6.
ii) Insertion: Lateral lip of the bicipital groove.
iii) Fiber Direction: Generally from medial to lateral.
iv) Actions: (All of glenohumeral joint)
(1) Adduction.
(2) Horizontal adduction.
(3) Internal rotation.
(4) Flexion.
(5) Extension
v) Notes / relationship to other musculoskeletal structures:
(1) Pectoralis major is a superficial chest muscle.
g) Biceps and Triceps (Covered Next Session)
2/11 © Blue Sky School of Professional Massage and Therapeutic Bodywork 9
MSAK101-II – Session 2 – Shoulder Muscles
4) MOTION OF SHOULDER GIRDLE
ACTION
AGONIST SYNERGIST
Elevation Upper Trapezius
Levator Scapulae
Rhomboids
Depression Lower Trapezius Pectoralis Minor
Retraction Rhomboids Middle Trapezius
Protraction Serratus Anterior Pectoralis Minor
Upward Rotation Lower and Upper Trap
Serratus Anterior
Downward Rotation Pectoralis Minor Rhomboids
Levator Scapulae
5) MOTION OF SHOULDER
ACTION
Normal ROM AGONIST SYNERGIST
Flexion 180° Anterior Deltoid
Coracobrachialis
Pectoralis Major
Biceps Brachii
Extension 45° Latissimus Dorsi
Posterior Deltoid
Teres Major
Triceps Brachii
Adduction 45° Pectoralis Major
Latissimus Dorsi
Ant and Post Deltoid
Coracobrachials
Teres Major
Abduction 180° Middle Deltoid
Supraspinatus
External rotation 40 - 45° Infraspinatus
Teres Minor
Posterior Deltoid
Internal rotation 55° Subscapularis
Pectoralis Major
Latissimus Dorsi
Teres Major
Anterior Deltoid
Horizontal Adduction Pectoralis Major
Coracobrachialis
Anterior Deltoid
Bicheps Brachii
Horizontal Abduction Posterior Deltoid
Infraspinatus
Latissimus Dorsi
Teres Minor