Extraneural pressures affecting the ulnar nerve at the elbow

Using fresh cadaveric arms, extraneural pressures were recorded along the path of the ulnar nerve at the elbow using a fine silastic cannula. Significant pressure increases occurred when the elbow was flexed beyond a right angle, and concomitant shoulder abduction further raised the pressures recorded at the cubital tunnel and post-condylar groove. Surgical release of the cubital tunnel decreased pressures in the post-condylar groove by approximately 50 per cent when the elbow was fully flexed, whereas clamping the flexor carpi aponeurotic arch significantly increased extraneural pressures in the groove, presumably by preventing accommodative changes in neural relationships.