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Rotator Cuff Injury

Rotator Cuff at a Glance

Understanding the Rotator Cuff

Damage to the rotator cuff is one of the most common causes of shoulder pain.

Rotator cuff: A group of four tendons that stabilize the shoulder joint.

Each of the four tendons hooks up to a muscle that moves the shoulder in a specific direction. The four muscles whose tendons form the rotator cuff are:

The subscapularis muscle, which moves the arm by turning it inward (internal rotation);
The supraspinatus muscle, which is responsible for elevating the arm and moving it away from the body;
The infraspinatus muscle, which assists the lifting of the arm during turning the arm outward (external rotation);
The teres minor muscle, which (like the infraspinatus) helps in the outward turning (external rotation) of the arm.

View the Shoulder Joint

Now that we understand how shoulder muscles work, let's have a look at the shoulder joint where rotator cuff injuries occur.

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Rotator Cuff Injury Overview

A rotator cuff injury is an injury to one or more of the four muscles in the shoulder. This shoulder injury may come on suddenly and be associated with a specific injury such as a fall (acute), or it may be something that gets progressively worse over time with activity that aggravates the muscle (chronic). Occasionally, even a simple act like rolling over in bed can result in a rotator cuff injury.

The type of injury can range from an inflammation of the muscle without any permanent damage, such as tendinitis, to a complete or partial tear of the muscle that might require surgery to fix it.

The shoulder joint connects the upper arm to the upper part of the body. It consists of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone).

Many different ligaments (rubber band-like structures that attach bone to bone) are involved in stabilizing the shoulder joint, particularly in the front. The muscles of the rotator cuff stabilize the back of the shoulder joint. These muscles help to keep the head of the humerus in place against the shoulder blade. The rotator cuff is comprised of four muscles (supraspinatus, infraspinatus, teres minor, and subscapularis).