The Rotator Cuff is commonly talked about in sport and exercise. It plays an important role in shoulder function by stabilising the shoulder. Commonly mistaken as a singular muscle in the shoulder that is responsible for rotation of the arm. Well the Rotator Cuff is actually a group of muscles that attach to the head of the humerous and is much more complex.
The arm is suspended, with very little bony support. The socket joint of the shoulder blade, in which the head of the humorous sits, is a very shallow ball and socket joint. The shoulder joint is then supported by, tendon, and ligament that attach the arm to the thoracic architecture. This arrangement creates a great deal of mobility but also poses a problem with regard to joint stability in high-velocity or high-force conditions.
The Muscles of the Rotator Cuff
The image on the left is a front on view of the shoulder. The rib cage has been removed and is showing the under side of the shoulder blade. Subscapularis is a fan like muscle that origins from the underside of the shoulder blade and inserts on the front of the humerus. Think up and under your arm pit. This muscle of the Rotator Cuff is hard to find and can become tight, coursing mobility restrictions.
The image on the right is a rear view of the shoulder. The Trapisious muscle (Traps) have been removed from this image and would sit over the Rhomboideus.
The Rhomboideus origin from the spine and attach to the edge of the shoulder blade. They play a big part in controlling and stabilising the shoulder blade, allowing the rest to do their job. If Rhomboideus are weak or inactive, due to shoulder sitting in a slumped position, the balance of stability of the Rotator Cuff can be thrown out. The Rhomboids must hold the shoulder blade stable to allow the rest to function correctly.
Supraspananis, Inraspananis and Teres minor all originate from the edge of the shoulder blade and attach to the back of the humorous. Now these guys can take a beating. They are responsible for stabilising the shoulder in many different ranges of movement. It is important to keep these guys healthy, strong and functioning. They are typically where sports injuries are found.
Teres Major is a small muscle that originates from the bottom point of the shoulder blade and inserts to the front of the humorous. You may feel this muscle after a big pull up workout, due to its support to the Lats. Responsible for stabilisation and assistance in pulling the arm down from an overhead position.