Partially overlapping territories of nerves to hindlimb foot skin demonstrated by plasma extravasation to antidromic C-fiber stimulation in the rat.

The innervation territories of the cutaneous nerves to the hindfoot were examined in the rat. Plasma extravasation of Evans blue to antidromic stimulation of C-fibers in the saphenous, sural, peroneal and tibial nerves was the means to determine the innervation areas. A high degree of bilateral symmetry was found for the territory of each nerve in individual rats. Stimulation of pairs of nerves, one on each side, that innervate neighboring skin regions revealed the existence of overlapping territories for all pairs of nerves. The area of overlap was greatest on the toes and just proximal to the toes on the dorsum of the foot, whereas overlap on the volar aspect of the foot was minimal. The need to consider the existence of overlapping cutaneous innervation in normal animals in studies involving collateral sprouting after nerve injuries is discussed.