Anatomy of the Shoulder and Elbow
The shoulder joint is a universal ball and socket joint with the greatest three-dimensional range of movement of any joint in the body. The shoulder joint is formed by the humeral head (ball) and the glenoid (socket). The joint is surrounded by a sack (capsule), which is thickened in areas to form strong ligaments. The muscles and tendons of the rotator cuff surrounding the joint contribute to both stability and strength of the shoulder.
The elbow joint is a hinge joint between the lower end of the humerus and the upper ends of the forearm bones, the radius and ulna. The elbow allows the movements of flexion, extension and forearm rotation. It is an extremely stable joint.