Motor fibers in human sural nerve.

Two cases of anomalous innervation of the abductor digiti quinti muscle of the foot via sural nerve are described. This anatomical variation can be discovered only when antidromic sensory conduction is investigated. The possibility that the abnormality could explain some reports of degenerated myelinated fibers in sural nerve biopsies of patients with amyotrophic lateral sclerosis is underlined.