Sensory innervation of the raccoon forepaw: 3. Cutaneous domains and organization of nerves innervating the raccoon forepaw.

This report summarizes single-fiber and multifiber data from the median, ulnar, dorsal ulnar, and superficial radial nerves innervating the raccoon forepaw with respect to the cutaneous domains innervated by each nerve. The median nerve was found to innervate the ventral surface of the first four digits and the radial two-thirds of the palm. Its innervation extended onto digit 5 in some animals. The palmar branch of the ulnar nerve innervated digits 4 and 5 and the ulnar half of the palm. The superficial radial nerve innervated the dorsal surface of the first four digits and the radial two-thirds of the forepaw, whereas the dorsal branch of the ulnar nerve innervated the ulnar half of the paw and digits 4 and 5. Overlap of adjacent nerves was verified in several cases by recording from two nerves in the same animal. The domains of the ventral and dorsal nerves overlapped at the borders of glabrous and hairy skin, particularly around the claws. Fiber types were not strictly grouped within particular fascicles according to either spatial or functional characteristics. However, there was a tendency toward overrepresentation of different modality and submodality types in different fascicles. The relevance of the overlap zones and autonomous zones of these nerves to experiments on central effects of peripheral nerve injury is discussed.