Components of the Rotator Cuff
The arm has a greater range of motion than any other part of the body. You can move your arm up, down, forward, backward, inward and outward, as well as rotate it. Much of this range of movement is made possible by the rotator cuff, a complex arrangement of muscles and tendons that attach the humerus (upper arm bone) to the bones in the shoulder via a ball-and-socket joint, known as the glenohumeral joint.
There are three bones attached to the rotator cuff:
- Humerus- upper arm bone
- Scapula- shoulder blade
- Clavicle- collar bone
There are four muscles in the rotator cuff:
- Supraspinatus muscle- a narrow muscle running from above the spine, or ridge, of the scapula to the humerus. It lifts the arm out to the side, away from the body
- Infraspinatus muscle- a large, thick triangular-shaped muscle that covers most of the back side of the scapula and connects it to the humerus. It acts to rotate the arm and also provides stability to the shoulder.
- Teres minor muscle- a narrow muscle that extends down at an angle from the scapula to the humerus. It lifts the arm away from the body, and rotates the arm.
- Subscapularis muscle- a triangular-shaped muscle located in the front of the scapula, attaching the scapula to the humerus at the shoulder joint. It serves to rotate the arm and helps to stabilize the shoulder.
Rotator Cuff Injuries
Injuries to the rotator cuff are quite common, since this area of the body is used frequently for so many different daily activities. Tendons or muscles may become inflamed, strained or even torn. This can happen from overuse due to repetitive work activities such as hammering, painting, plastering, or carrying heavy loads over the shoulder for long periods of time.
The rotator cuff can also become injured from playing sports that involve throwing or swinging the arm, such as baseball, football, tennis or bowling, as well as weightlifting, which can put a strain on the muscles.
Symptoms of Rotator Cuff Injury
The main symptom of rotator cuff injury is pain in the shoulder, especially when you raise your arm overhead, to the side or to the back. It may also be painful to sleep in certain positions. Sometimes you may also experience weakness in the arm.
Pain may be due to strained muscles, inflamed tendons (tendonitis) or irritated or inflamed bursa, a sac filled with fluid that is located in the shoulder joint (bursitis).
If the pain is severe or continuous even when you aren’t moving or using your arm, you may have a tear in one of the muscles.
Treatment of Rotator Cuff Injury
Depending on the nature and severity of the injury, treatment may involve physical therapy or steroid injections. Surgery may be required to repair severe damage to the rotator cuff such as a badly torn muscle.