Electrophysiologic studies of the cutaneous nerves of the head of the dog.

The cutaneous nerves of the head of the dog were investigated in 16 barbiturate-anesthetized dogs. The electrophysiologic demonstration of afferent impulses in a given cutaneous nerve to the movement of hairs within an area of skin was used to delineate the nerve's cutaneous area (CA) of innervation. In this manner, the CA for the cutaneous branches of the trigeminal nerve, the facial nerve, and the 2nd, 3rd, and 4th cervical nerves were determined. The CA of adjacent cutaneous nerves were found to overlap extensively. The portion of a nerve's CA which was solely innervated by it was termed the autonomous zone. Most of the CA of the head was innervated by branches of the trigeminal nerve. The internal auricular branches of the facial nerve innervated the majority of the concave surface of the pinna. The branches of the 2nd cervical nerve supplied a large CA which extended from the caudal intermandibular space to the dorsal midline and apex of the pinna. The CA of the branches of the 3rd and 4th cervical nerves occupied much of the cervical area cranial to the scapula and caudal to the hyoid apparatus. A CA was not found for the 1st cervical nerve.