Your rotator cuff is made up of four muscles and their tendons which allow you to move your arm away from your body. These muscles and tendons connect your upper arm bone with your shoulder blade and help to hold the ball of your upper arm bone firmly in your shoulder socket.
Rotator cuff injuries often occur as a result of microtrauma caused by repetitive movement in occupational or sporting activities. The rotator cuff muscles are put under a great deal of strain during racquet sports and other activities where the arm is frequently above the head.