The capsular ligament of the shoulder is surrounded and reinforced by muscles, tendons, and ligaments, which are largely responsible for keeping the adjoining parts together. A capsule is a membrane or sac enclosing a body part, usually a joint. The joint capsule of the shoulder is attached along the outside ring of the genoid cavity and the anatomical neck of the humerus. Although it completely covers the joint, the capsule is very loose and by itself would be unable to keep the bones of the joint in close contact without the aid of the fibers around it.