The shoulder joint is a synovial ball-and-socket joint between the head of the humerus bone and the shallow glenoid cavity of the scapula. It has a thin, lax capsule strengthened by rotator cuff muscles and ligaments. The joint allows wide range of movement including flexion, extension, abduction, adduction, medial and lateral rotation, and circumduction. It is prone to dislocations, especially anterior dislocations, due to its anatomy. Recurrent dislocations often require surgical repair to reattach the capsular ligaments.