The typical site for compression of the suprascapular nerve is the suprascapular notch (foramen) on the superior margin of the scapula.
The patient’s apparently minor injury damaged the fibrocartilaginous glenoid labrum, which allowed a cyst to form and pass along the superior border of the scapula to the suprascapular notch (foramen), where the cyst compressed the suprascapular nerve.