Electrophysiologic study of anomalous innervation of the intrinsic hand muscles

With electrophysiological methods the possible presence of anomalous innervation and/or of anastomosis between the median and ulnar nerve in the intrinsic hand muscles was studied in 34 limbs. The abductor pollicis brevis was supplied by the ulnar nerve in 12% to 38%, the first dorsal interosseus by the median nerve in 4.2% to 19.6%; the abductor digiti minimi was in no case supplied by the median nerve.