The name “Rotator Cuff” is used to describe the group of small but important muscles around the shoulder joint and their tendons that helps control shoulder joint movement. The supraspinatus is at the top of the joint, the subscapularis is in front and the infraspinatus and teres minor are at back side. These muscles insert or attach to the humeral head by way of their tendons. The tendons fuse together giving rise to the term “cuff.” Although each muscle acting alone may produce an isolated rotational movement of the shoulder, the role they play together is to help keep the humeral head (ball) centered within the glenoid (socket) as the powerful deltoid and other larger shoulder muscles act to lift the arm overhead.
Acromion a bony projection forms the roof of shoulder apartment. Between the rotator cuff tendons and the acromion is a protective fluid-filled sack called a “bursa”. With normal humeral elevation there is some contact between the rotator cuff, the bursa, and the acromion. A healthy and strong rotator cuff holds the humeral head down in the socket and minimizes the upward pressure on the acromion.