Suprascapular Nerve Entrapment

Suprascapular nerve entrapment is an uncommon nerve condition in the shoulder, causing pain and weakness. It involves compression of the suprascapular nerve at the top or back of the shoulder, usually caused by a ligament, a cyst from the shoulder, or excessive stretching. The suprascapular nerve passes in a groove in the shoulder blade (scapula), under a ligament, then under the supraspinatus muscle (which it supplies) on the top of the shoulder, and then under another ligament before it divides and supplies the infraspinatus muscle in the back of the shoulder. The nerve may be injured before it supplies the supraspinatus muscle (thus causing weakness of both the supraspinatus and infraspinatus) or after it supplies the supraspinatus (causing weakness of only the infraspinatus). These muscles, which are part of the rotator cuff, are important in stabilizing the shoulder and assisting in raising and rotating the shoulder and arm.