<Originals> Anatomical Studies on the Suprascapular Nerve. 1 : Findings in Gross Anatomy

The purpose of this study was to examine gross anatomy of the suprascapular nerve using 20 cadavers (14 male and 6 female), with special reference to the anomalous branch to the supraspinatus muscle and funicular pattern in the scapular notch. The branch to the supraspinatus muscle did not ramify proximal to the scapular notch, whereas the suprascapular artery passed under the superior transverse scapular ligament in 17.5% of the cadavers. Fourty percent of the scapular notches were type II by the classification of Rengachary. There was no adhesion between the suprascapular nerve and superior transverse scapular ligament which varied in size and toughness; the inferior transverse scapular ligament was, however, thin in 72.5%. Pseudoneuromas found just proximal to the superior transverse scapular ligament had no correlation with supraspinatus and infraspinatus muscle atrophy, which were not remarkable. The branch to the supraspinatus muscle superomedial in the scapular notch were located just below the superior transverse scapular ligament where friction neuritis was said to be occasionally seen. The present findings suggest that infraspinatus muscle atrophy is caused by suprascapular entrapment neuropathy at the spinoglenoid notch rather than at the scapular notch