Spinoglenoid septum: a new anatomic finding

The spinoglenoid ligament has been implicated in compression of the suprascapular nerve in cases with isolated atrophy of the infraspinatus muscle. We dissected 32 shoulders of 16 embalmed cadavers. We could detect a spinoglenoid ligament in only 5 shoulders, and it was thin, loose, and weak. Instead of the spinoglenoid ligament, we observed a septum formed by the thickening of the fascial cover of the distal third of the supraspinatus and infraspinatus muscles. It originated from the spinoglenoid notch and extended into the posterior capsule. We named this structure the spinoglenoid septum. The suprascapular nerve passed between the bony margin of the spinoglenoid notch and the medial concave margin of the spinoglenoid septum. This septum may be a cause of dynamic compression of the suprascapular nerve.