The rotator cuff is made up of tendons and muscles in the shoulder. The tendons and muscles connect the upper arm bone with the shoulder blade and they hold the ball of the upper arm bone in the shoulder socket. The combination means greater range of motion of any joint in the body. A rotator cuff injury can include any type of irradiation or damage to the tendons and muscles. Causes of an injury can include lifting, falling, and repetitive arm activities (usually those that are done overhead like throwing a baseball). About 50 percent of rotator cuff injuries can heal with self-care or exercise therapy.