the scapula (shoulder blade), the humerus (upper arm bone), and the clavicle (collarbone). The
rotator cuff connects the humerus to the scapula. The rotator cuff is formed by the tendons of four separate muscles: the supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles raise and rotate the arm by pulling on the tendons. As the arm is raised, the rotator cuff keeps the humerus bone tightly in the socket of the scapula.