A treatable cause of infraspinatus muscle atrophy is compression of the supra scapular nerve within the spinoglenoid notch by a ganglion cyst.
This is most commonly associated with posterosuperior impingement syndrome.
A tear its present in the posterosuperior labrum leading to the formation of a ganglion.
This passes in a posterior and medial direction until it reaches the notch where it can expand and compress the suprascapular nerve.
