The shoulder is a complex, highly mobile joint designed to provide the highest amount of motion of any joint in the body. The rotator cuff is a collection of four muscles that surround the shoulder joint. Its primary responsibility is to promote stability of the joint. The muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. On top of the rotator cuff is the subacromial/subdeltoid bursa.
The rotator cuff can be acutely torn, such as with a fall or accident, but much more commonly we see slow and progressive wear over time that results in pain without a specific incident. The tendons first become thickened and irritated, but with repetitive insults, like rubbing a worn cloth over and over, small tears can develop. With more time big tears can develop until it separates from the attachment point of the humerus.
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