Alteration in connections between muscle and anterior horn motoneurons after peripheral nerve repair.

The connections between the spinal cord and lower leg muscles of the rat are significantly altered by repair of the intervening sciatric nerve. Muscles supplied by the peroneal branch of the sciatic are innervated by fewer motoneurons after sciatic repair. Many of these neurons originally innervated the peroneal muscles, and others formerly served the antagonistic tibial muscles. Perikarya in the size range of alpha motoneurons regained peripheral connections with greater frequency than those in the gamma range. There are thus postoperative defects in the extent and specificity of alpha reinnervation as well as in the degree of gamma control.