The shoulder joint classifies as a ball and socket joint; however, the joint sacrifices stability for mobility. The glenoid is a shallow rim, and one description is as looking like a golf ball on a tee or a basketball on a dinner plate. The rotator cuff consists of four muscles originating on the scapula and inserting on the superior humeral head to improve stability. The subscapularis inserts on the lesser tubercle of the humerus, and it functions as an internal rotator. The supraspinatus mu...
