If you watch much in terms of sports or you have simply had a shoulder injury yourself, you have probably heard of the rotator cuff. I have heard it called many things in the past including rotor cup or rotisserie cup; but, just to clarify, the actual name is rotator cuff. There are several muscles that work together to form this structure situated at shoulder.
The rotator cuff consists of four muscles: the supraspinatus, infraspinatus, subscapularis, and teres minor. Each of these muscles performs different duties, but they also work together to supply stability to the shoulder joint. The shoulder joint is what is called a ball-and-socket joint, which is the same as the hip joint. The hip joint, however, has a deeper socket and a lining called the acetabulum which helps to stabilize the head of the thigh bone (femur) in the socket of the hip bone (pelvis). At the shoulder, the socket (glenoid) is shallower than the hip socket, so the arm bone (humerus) needs help from muscles around the joint to keep it stable. That is where the rotator cuff comes in.
Each of the rotator cuff muscles attaches to both the shoulder blade (scapula) and the arm bone (humerus) to form a “cuff” around the shoulder. The image to the right gives an overview of the anatomy of the rotator cuff and where each muscle sits at the shoulder.
Unfortunately, if the rotator cuff is damaged in any way, the stability at the shoulder joint is reduced and movements that were typically comfortable become painful. Injuries most commonly occur with repetitive overhead activities; thus making individuals in certain occupations including carpentry, painting, and sports (ex. baseball and tennis) more prone to injuring the rotator cuff. You don’t HAVE to be an athlete to sustain such an injury, however. The older you are, the higher your risk is for injuring this group of muscles, especially if your muscles are already weak. I have treated people who sustained a rotator cuff injury simply while putting up Christmas decorations. Additionally, some people have what is called a hooked acromion. With this condition, one of the bone structures (acromion) that sits overtop of the supraspinatus muscle hooks downward; so the muscle is more susceptible to injury from the friction of this bone rubbing the top of the muscle/tendon.
All in all, there are several possible causes for a rotator cuff injury, and the treatment can vary just as much depending on the severity of the condition. Our next blog will address treatment approaches for rotator cuff injuries.