Electrophysiologic and behavioral studies of the cutaneous nerves of the concave surface of the pinna and the external ear canal of the dog.

: The investigation used 2 methods to study the cutaneous innervation of the concave surface of the pinna of the dog: electrophysiologic and behavioral. The cutaneous innervation of the external ear canal was studied, using electrophysiologic methods. On one side of each dog, the area of remaining sensitivity for the 3 internal auricular branches of the facial nerve (InAuB-FN) was determined by sectioning the rostral auricular nerve, dorsal cutaneous branch of the second cervical nerve, and great auricular nerve and then examining the dogs 1 week later. The cutaneous area (CA) of each branch of the InAuB-FN was then determined electrophysiologically. These individual CA were combined to obtain a composite cutaneous area (Comp-CA) for the InAuB-FN. By comparing the Comp-CA with the area of remaining sensitivity, it was determined that they defined essentially the same regions. On the opposite side of each dog, the InAuB-FN were surgically transected and the resultant areas of anesthesia were determined approximately 1 week after the sectioning was done. The cutaneous region thus delineated represented a zone solely innervated by these branches of the FN. Next, the CA for the rostral auricular nerve, dorsal cutaneous branch of the second cervical nerve, and great auricular nerve to the pinna's concave surface were determined electrophysiologically in each dog. The cutaneous zone enclosed by the margins of the CA of these 3 nerves represented the composite autonomous zone for the InAuB-FN. The behaviorally determined area of anesthesia was essentially the same area as the composite autonomous zone. The skin lining the vertical portion of the external ear canal was supplied by all 3 branches of the InAuB-FN. The skin lining the horizontal portion of the external ear canal was supplied by the lateral branch of the InAuB-FN and the external acoustic meatus branch of the auriculotemporal nerve.