Arthroscopic relationship of the axillary nerve to the shoulder joint capsule: an anatomic study

Twelve right shoulders in fresh cadavers were dissected to determine the relation of the axillary nerve to the shoulder capsule and glenoid. Needles transfixed the nerve to the capsule and into the shoulder joint. Arthroscopy was performed to determine the location of the needles on the glenoid clock. The needles were then removed and the position of the shoulder changed to determine the effect on the position of the axillary nerve. The axillary nerve was held to the shoulder capsule with loose areolar tissue in the zone between 5 and 7 o'clock and was close to the glenoid in the neutral position, in extension, and in internal rotation. With shoulder abduction, external rotation, and perpendicular traction, the capsule became taut and the axillary nerve moved away from the glenoid. Abduction, external rotation, and perpendicular traction increase the zone of safety during arthroscopic anteroinferior capsulotomy adjacent to the glenoid between the 5 and 7 o'clock positions.