Rotator cuff tears are a common cause of pain and disability in adults. The rotator cuff is made up of four muscles and their tendons that combine to form a "cuff" over the head of the humerus. The four muscles include the supraspinatus, infraspinatus, subscapularis and teres minor. The rotator cuff helps to lift and rotate the arm and to stabilize the ball of the shoulder within the joint. Most tears occur in the supraspinatus, but other portions of the rotator cuff can be involved.