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Body Surface

The primary surface landmarks of the shoulder joint are associated with the clavicle and scapula ( spine, acromion and coracoid process). The skin overlying the shoulder joint is innervated by the intercostobrachial and upper lateral cutaneous nerve of the arm, and cutaneous branches of ventral rami C3, C4 and T2.

Skeleton and Joints

The bones and joints associated with the shoulder are the clavicle and scapula articulating at the acromioclavicular joint, the scapula and humerus articulating at the shoulder (glenohumeral) joint. The acromial clavicular joint is the articulation between the distal end of the clavical and the acromion of the scapula supported by the acromioclavicual and coracoclavicular ligaments. The shoulder joint is the articulation between the humeral head and the glenoid fossa of the scapula. This joint is classified as a ball and socket articulation with three degrees of freedom allowing for flexion/extension, abduction/adduction and medial (internal) / lateral (external) rotation of the humerus. The glenoid fossa has a fibrocartilagenous rim, the glenoid labrum. The joint is enveloped by a fibrous joint capsule and is supported by the tendons of the rotator cuff muscles (supraspinatus, infraspinatus, teres minor and subscapularis) and the long heads of the triceps and biceps brachii muscles. The capsule is reinforced anteriorly by the three (superior, middle and inferior) glenohumeral ligaments.

Muscles

Muscles of the pectoral region, shoulder, and anterior and posterior compartments of the arm are active during movements of the glenohumeral joint.

Innervation

The supraspinatus, axillary, pectoral, subscapular, musculocutaneous and radial nerves innervate the shoulder joint.

Blood Supply

Branches of the suprascapular, circumflex scapular, and anterior and posterior circumflex humeral arteries supply the glenohumeral joint.