ANATOMY

Shoulder

The shoulder joint is formed by the long bone of the upper arm (humerus) and the shoulder blade (scapula). The head of the humerus and the end of the scapula (the glenoid) form a highly flexible ball and socket which is cushioned within the joint cavity by articular cartilage and stabilised by a ring of strong fibrous cartilage, (the labrum) which surrounds the glenoid.

The shoulder blade protects the joint at the front (the coracoid process) and at the back (the acromion), and the bones are bound together with ligaments. The biceps tendon attaches the biceps muscle at two anchor points on the shoulder and functions to bend the elbow and rotate the forearm.

Four flat tendons each connect to smaller muscles which form the rotator cuff, passing around the shoulder to then fuse together to encircle the shoulder blade so that it can rotate upward, inward or outward.