Effect of Crossing Nerves to Antagonistic Limb Muscles in the Monkey

CROSSING of nerves to antagonistic limb muscles or transplantation of the muscles themselves has been found to produce in the rat disorders of motor coordination directly correlated with the anatomic rearrangements. For example, transposition of the flexor and extensor muscles of the shank¹or interchange of the nerve supply of these muscles²produced in each case a full reversal of the flexor-extensor movements of the ankle. A comparable reversal of motor action in the forelimb was shown to follow the crossing of nerves and the transposition of muscles acting on the elbow joint.³Sensory nerve crosses from one hindfoot into the contralateral hindfoot also were found to result in false reference of sensations and a maladaptive reversal of the withdrawal reflexes.⁴All these functional derangements persisted permanently in the rat without correction by reeducation. Numerous clinical reports indicate, however, that man is capable of achieving motor