Rotator Cuff Tears Commonly Associated with Auto Accidents The rotator cuff holds the upper arm bone (humerus) into the shoulder socket. The rotator cuff is comprised of four muscles that come together as tendons and form a cover (cuff) over the top (ball) of the upper arm bone (humerus). The rotator cuff attaches the humerus to the shoulder blade allowing the arm to lift and rotate. Think of the rotator cuff as Read More