[The accessory deep peroneal nerve. Electrophysiologic study].

The extensor digitorum brevis muscle is innervated by the deep peroneal nerve. In some cases it has an additional innervation by the accessory deep peroneal nerve, a branch of the superficial deep peroneal nerve. The motor nerve conduction study with detection on the extensor digitorum brevis allows to detect such an anatomical variation. It has been found in twelve cases out of 67 subjects. In two cases it was bilateral and in two other cases the extensor digitorum brevis muscle was innervated by the accessory deep peroneal nerve alone. That anatomical variation has to be known in order to avoid errors in interpretating the peroneal motor nerve conduction velocity.