What is the rotator cuff?

The rotator cuff is made up of four muscles and their tendons. These allow you to move your arm away from your body.

A tear in this group of muscles is commonly accompanied by pain when in motion and also at night. Weakness of the arm may occur if the condition is allowed to deteriorate. If the tear becomes very large, the muscles around the shoulder may waste away to the point where you can see it.

How does the shoulder work and why does the rotator cuff tear?

Because of the complexity of muscles and ligaments and the lack of bony constraints, the shoulder is capable of extensive motion.

The shoulder is a large ball-and-socket joint. It is made up of bones, tendons, muscles and ligaments which hold the shoulder in place but also allow movement. Bones of the shoulder joint include: the clavicle (collar bone), scapula (shoulder blade), and humerus (arm bone). The clavicle attaches the shoulder to the sternum and holds it out away from the body. (Fig. 1)

The clavicle connects with the shoulder blade at the acromioclavicular joint (A.C. joint or the acromion). The rounded head of the humerus, or arm bone, rests against the socket in the shoulder blade.

The rotator cuff is the group of muscles and tendons which stabilizes the shoulder and holds the arm bone within its shallow socket (the glenoid). This group of muscles includes: the teres minor, supraspinatus, infraspinatus, and subscapularis.

Most often, the tear involves the supraspinatus tendon. In these cases, the tear occurs when the tendon rubs over a bone spur during a long period of time.

If I think I have a rotator cuff tear, when should I call my doctor?

Call your doctor when you feel continuous weakness and pain in your shoulder. The most common symptom of a torn rotator cuff is pain, particularly at night. This night pain may be severe enough to keep you from sleeping. Call your doctor if you are experiencing this type of discomfort.

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