Two joints facilitate shoulder movement. The capsule is a soft tissue envelope that encircles the glenohumeral joint. It is lined by a thin, smooth synovial membrane. The bones of the shoulder are held in place by muscles, tendons, and ligaments. Tendons are tough cords of tissue that attach the shoulder muscles to bone and assist the muscles in moving the shoulder.
Ligaments attach shoulder bones to each other, providing stability.
For example, the front of the joint capsule is anchored by three glenohumeral ligaments.