The rotator cuff is an important structure in the shoulder area. Otherwise known as the rotor cuff or rotator cup, it is a group of tendons and muscles that help stabilize the shoulder joint. The rotator cuff is located on both sides of the shoulder joint and they specifically act to keep the humeral head on the glenoid fossa.

The Anatomy of the Rotator Cuff
The rotator cuff is not a single structure in the shoulder joint. It is composed of four muscle groups such as the Supraspinatus muscle, Infraspinatus muscle, Teres minor muscle and the Subscapularis muscle. All of these muscle fibers are connected with each other to form the rotator cuff. These muscles also allow for the abduction and internal and externals rotation of the arms. The muscle groups are innervated by various nerves to help them contract effectively. The suprascapular nerve innervates the Supraspinatus muscle and Infraspinatus muscle, the axillary nerve innervates the Teres minor muscle and the upper and lower subscapular nerve innervates the Subscapularis muscle.

Functions of the Rotator Cuff
The rotator cuff serves various functions for the shoulder joint including:

• Provides stability for the glenohumeral joint
In the shoulder joint, the glenoid fossa is a shallow socket for the humeral head. This makes the rotator cuff an important structure in the shoulder joint because it surrounds the humeral head to prevent it from getting outside the socket. This ensures a smooth shoulder joint movement and is responsible for the overhead movement of the arms without the humerus being dislocated out from the shoulder.
• Allows for the abduction of the arms
When the arms are moved outward away from the body, the rotator cuff serves a very important role. The rotator cuff acts by compressing the glenohumeral joint in order to allow the muscles in the upper arm to elevate the arm further. Without the rotator cuff, the upper arm muscles such as the deltoid may not be able to abduct the arm effectively because the humeral head may ride off the socket of the shoulder joint.

The rotator cuff is indeed very important for the shoulder joint and any injury to the tough muscle band may lead to injuries in the shoulder joint as well. Some of the most common injuries that develop in the rotator cuff include:

• Rotator cuff tear- When the rotator cuff is overused like in the case of sports that involve overhead movement of the arms such as baseball, tennis and the like, the cuff may be torn leading to pain in the area. The tearing may also lead to reduced range of motion in the arms especially the overhead movement and arm abduction.
• Nerve impingements- Nerve impingements may also occur in the nerves that innervate the various muscle bundles in the rotator cuff. As the nerves become compressed, there may be feelings of weakness in the shoulders as well as tingling and numbness on the shoulders and arms.

Since the rotator cuff is an important structure in the shoulder, prevention of possible injuries should be employed and the most effective means to do this is to perform stretching exercises on the shoulders.