An injury to the rotator cuff can be very painful, not to mention make simple tasks like putting on a shirt or picking up a gallon of milk very difficult. When I see a patient who has a torn rotator cuff, rotator cuff tendinitis, or rotator cuff “impingement,” I spend a good amount of time showing them what the rotator cuff is and describing how it works.
The rotator cuff is a group of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. The muscles form a cuff around the humerus (long bone of the arm) to keep the ball of your shoulder joint seated properly in the socket. The muscles attach the shoulder blade to the humerus and act to elevate the arm and rotate it back and forth.
The rotator cuff maintains shoulder stability. The main joint of the shoulder is shaped like a ball and socket. The socket (glenoid) is relatively small and shallow when compared with the ball end (humerus). A good analogy is to picture how a golf ball (humerus) sits on a tee (glenoid). The deltoid is a large and powerful muscle that pulls the arm up when you reach up above your head. It pulls on the top of the “golf ball” in an upward direction. The rotator cuff muscles help to counteract the upward pull of the deltoid, by producing a force that pulls in the opposite direction. The rotator cuff pulls on the “golf ball” on the side resting on the tee. This force keeps the ball (humerus) in the socket (glenoid), or the “golf ball” from rolling up and off the “tee.” When the arm is raised and these forces are balanced, the golf ball rotates on the tee. When the deltoid pull is not balanced out by the pull of the rotator cuff, it rolls off the tee and can result in painful conditions. It can cause impingement, rotator cuff disorders, and early shoulder joint degeneration.
Now that you know a little more about where these muscles are located and how they function, you can appreciate how important they are in rehabilitating a painful shoulder. If you are having shoulder pain, find a physical therapist. You can find me here.