Three different joints articulate at the shoulder:

■ The glenohumeral joint. In this joint, the head of the humerus articulates with the shallow glenoid fossa of the scapula. This joint is deeply situated and normally not palpable. It is a ball-and-socket joint, allowing the arm its wide arc of movement—flexion, extension, abduction (movement away from the trunk), adduction (movement toward the trunk), rotation, and circumduction.

■ The sternoclavicular joint. The convex medial end of the clavicle articulates with the concave hollow in the upper sternum.

■ The acromioclavicular joint. The lateral end of the clavicle articulates with the acromion process of the scapula.

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