The rotator cuff is a group of four muscles and tendons that surround the shoulder joint. These muscles and tendons provide stability in the shoulder, attaching around the head of the humerus bone, encircling it like a cuff. These four muscles include:
- Infraspinatous: This muscle is positioned more behind the shoulder joint. It helps to externally rotate the arm, for example, when you are throwing a ball.
- Supraspinatous: This muscle forms the upper border of the rotator cuff. It helps you bring your arm away from your body.
- Subscapularis: This is the only rotator cuff muscle that is actually in front of the shoulder. It helps rotate the arm toward the body, such as when you touch your stomach.
- Teres Minor: This muscle primarily helps externally rotate the shoulder, but it also helps pull the arm into the body.