Parts of the Shoulder

The shoulder is the most flexible part of the body. The main joint in the shoulder is called the glenohumeral joint. This is where the arm bone (humerus) rests in a shallow socket called the glenoid. The bones in the shoulder are connected by ligaments, muscles, and other strong tissues. When the shoulder is healthy, you can move your arm in almost any direction (a full range of motion).

Front view of shoulder anatomy showing bones, muscles, tendons, and ligaments. Acromion is top part of shoulder blade. Rotator cuff is group of muscles and tendons that attach arm bone to shoulder blade and help shoulder move.  Humerus is arm bone. Humeral head is top part of arm bone shaped like ball and resting against shoulder socket. Scapula is shoulder blade. Glenoid is shallow socket that forms cradle for head of arm bone. Cartilage is smooth covering on ends of bones, cushioning them and allowing them to move without pain. Capsule is sheet of fibers that surround joint. Capsule is tough enough to keep joint stable yet flexible enough to allow it to move freely.