Rotator Cuff | Anatomy and Function

Anatomy of the Rotator Cuff

Rotator Cuff | Anatomy and Function

• Anatomy
• Function

Anatomy

Have you ever wondered what force provides motion to your shoulder and arms? 

Did you think that the deltoid muscles are the only ones responsible for that motion?

Well, the shoulder has a very complex structure with the highest mobility in the entire body. 

This calls for other muscles and ligaments to be key forces for stabilizing the shoulder and protects it against injuries. 

Speaking of stabilizers, the rotator cuff is the most important one of all.

The rotator cuff is a group of muscles and their tendons that have the main function of providing flexibility to the shoulder (Rotating it in a wide range of motion) and keeping the upper head of the humerus (ball) in the socket (Created by the connection of the scapula and the clavicle).

Four distinct muscles compose the rotator cuff, with three located posteriorly and one anteriorly. 

The ones at the back all originate from different levels on the scapula; they are the supraspinatus, infraspinatus and teres minor. 

On the other side of the scapular (Front) originates the subscapularis, which is a large flat muscle. 

All of the four rotaror cuff muscles attach to the upper portion of the upper arm bone (Humerus).

Function

As mentioned above, the rotator cuff muscles are critical in shoulder joint stabilization and movement. 

They also play a key role in moving the arm to different directions.

The three muscles located posteriorly (supraspinatus, infraspinatus and teres minor) are generally responsible for the external rotation of the arm.

This be it a rotation while the arm is down and moving to the opposite direction of the torso, or up in the air with the palm facing upward. 

The muscle attached anteriorly (Subscapularis), on the other hand, brings the arm in a rotational movement towards the torso with the palm facing downward at the end of the move.

However, each one of the four rotator cuff muscle has other specific functions. 

The supraspinatus helps with abduction of the arm and stabilization of the humerus keeping it in place. 

Both the infraspinatus and teres minor perform the lateral and external rotation of the arm; they extend the shoulder, rise the arm and rotate it away from the body. 

Lastly, the subscapularis holds the humerus to the shoulder blade and helps with lowering the arm and rotating it inward.