Muscles of the Shoulder Girdle

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Important Muscles:

• Extrinsic muscles attach upper limb to trunk.

• Trapezius, rhomboid major and minor, levator scapulae, latissimus dorsi, serratus anterior.

Scapulohumeral Muscles:

• Deltoid, supraspinatus, infraspinatus, teres major, teres minor, subscapularis and long head of triceps. The rotator cuff muscles (S.I.T.S.) include the supraspinatus, infraspinatus, teres minor and subscapularis muscles.

• The rotator cuff muscles initiate abduction.

• The deltoid muscle then takes over abduction.

Rotator Cuff Injuries:

There is a group of tendons of four muscles (S.I.T.S.) which enclose the glenohumeral joint on its posterior, superior and anterior aspects. It is the strongest element which reinforces the shoulder joint. The rotator cuff muscles, most commonly the supraspinatus, are frequently torn during forceful exercise (throwing a ball or heavy lifting or direct trauma). The degenerative inflammatory changes can also cause muscle tendons to rupture. Arm abduction in affected patients is very painful.

Winging of the Scapula:

An important movement of the scapula is to "slide" anteriorly and posteriorly along the posterolateral chest wall surface (protraction and retraction). The major muscle which causes protraction is the serratus anterior. When this muscle is weak or is not functioning (due to lack of innervation by the long thoracic nerve) the scapula will not be tightly held against the chest wall and may protrude outward, "wings," when protraction occurs. This problem is usually unilateral (i.e., only one side is affected).

Muscular Triangular Space:

Boundaries of the Muscular Triangular Space:

• Teres minor (superior border).

• Teres major (inferior border).

• Long head of the triceps (lateral border).

The muscular triangular space has as its contents the circumflex scapular artery.

Muscular Quadrangular Space:

Boundaries of the Muscular Quadrangular Space:

1. Teres minor and subscapularis tendon (superior border).

2. Teres major (inferior border).

3. Long head of triceps (medial border).

4. Surgical neck of humerus (lateral border).

The muscular quadrangular space has as its contents the axillary nerve and the posterior humeral circumflex artery.

Chapters on Shoulder Anatomy:

1. Arteries of the Axilla
2. Arteries of the Shoulder Girdle
3. Axillary Artery Aneurysm
4. Axillary Fat and Fascia
5. Axillary Nerve Block
6. Bones and Fractures of the Upper Limb
7. Boundaries of the Axilla
8. Breast Cancer and Axillary Lymph Nodes
9. Erb-Duchenne Palsy
10. Joints of the Shoulder Girdle
11. Klumpke's Paralysis
12. Lymph Nodes of the Axilla
13. Muscles of the Axilla
14. Muscles of the Shoulder Girdle
15. Notes on Shoulder Bursae
16. Roots and Trunks of the Brachial Plexus
17. Winged Scapula in Computer Programmer
18. Transient Axillary Paralysis
19. Variation of Brachial Plexus Structure
20. Veins of the Axilla

Additional Reading:

Histology and Cytology

1. Cell Components
2. Nervous Tissue
3. Muscle Tissue
4. Lymphoid Tissue
5. Integument
6. Respiratory System
7. Gastrointestinal System
8. Renal/Urinary System
9. Male Reproductive System
10. Female Reproductive System

Gross Anatomy

1. Back and Nervous System
2. Thorax
3. Abdomen, Pelvis, and Perineum
4. Upper Limb
5. Lower Limb
6. Head and Neck
7. Chest Wall
8. Shoulder

Anatomy Videos

1. Video of Musculoskeletal Examination in a Clinical Setting
1. Video of HEENT Examination in a Clinical Setting

Related Topics

1. Jugular Venous Distention Workup

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