3. The Shoulder

Figures 3.1 and 3.2 illustrates the surface anatomy of the glenohumeral joint of the shoulder. The shoulder is a ball and socket joint whose structure allows for an impressive range of motion (ROM), but at a cost. Unlike the very stable hip joint, which has a deep socket, the glenoid fossa is relatively shallow, and the humeral head is oversized with respect to the fossa. The labrum, a rim of cartilage around the glenoid fossa, helps increase the depth and stability of the shoulder joint, but the other soft tissues of the shoulder provide most of the joint’s stability. In order for proper functioning to occur, all these tissues (muscles, tendons, ligaments, and the labrum) must be functioning at proper tension. Disruption in any one of these can lead to dysfunctional shoulder motion and subsequent problems [1, 2].