The shoulder joint is a ball-and-socket joint formed between the head of the humerus and the glenoid fossa of the scapula. It has greater mobility but less stability than other joints. The joint is supported by ligaments, tendons of the rotator cuff muscles, and a loose fibrous capsule that allows for its wide range of motion. The glenohumeral joint works together with scapulothoracic movements in a rhythm during arm elevation.