A HISTOCHEMICAL-STUDY OF THE BICEPS BRACHII MUSCLE CROSS-INNERVATED BY INTERCOSTAL NERVES - 6 CASES OF BRACHIAL-PLEXUS INJURIES OPERATED WITH NERVE-CROSSING

Direct nerve-crossing of intercostal nerves from the lateral thorax to the musculocutaneous nerve was performed in 6 patients after spinal n erve root avulsion with brachial plexus palsy. Elbow flexion power was regained well enough to move against gravity and some resistance in a ll cases. The muscles were examined histochemically 4 (1-9) years afte r the operation. The intercostally-innervated biceps brachii muscle sh owed motor predominance of slow-twitch Type 1 fiber regeneration much more than that of fast-twitch Type 2 fiber in 5 of our patients. Our s tudy suggests that the motor nerves of slow-twitch fibers may have pri ority in peripheral nerve regeneration over those of fast-twitch fiber s.