Motor fibers in the sural nerve of humans.

Although motor fibers in the sural nerve were already described in three individuals, this nerve is considered purely sensory. We investigated the occurrence of motor fibers in 331 sural nerves of 207 individuals. We found motor fibers in 15 nerves (4.5%) or in 13 individuals (6.2%). The identification of motor fibers in the sural nerve before nerve biopsy has important implications for the interpretation of pathologic findings.