Capsule of The Shoulder Joint

A "capsule" is a membrane or sac enclosing a body part, usually a joint. "Capsular ligaments" are surrounded and reinforced by muscles tendons, and ligaments, which are largely responsible for keeping the adjoining parts together. 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. The joint capsule of the elbow has sides which are thickened by ulnar and radial collateral ligaments. The front surface of the capsule is reinforced by fibers from a muscle (brachialis) in the upper arm.