AFFERENT CONNECTIONS OF FACIAL NERVE

The central connections of the afferents of the facial nerve have been studied by the Nauta‐Gygax and Fink‐Heimer techniques in the rat, cat, and the rhesus, cynomolgus, and squirrel monkeys. Descending components that entered the spinal V and solitary tract were found in all species studied. The spinal V fibers terminated in the upper cervical dorsal horn, making a minor contribution to the various subdivisions of the spinal V nucleus, and are probably concerned with pain; the solitary fibers terminated in the solitary nucleus, predominantly at levels rostral to the obex. A few degeneration fibers were seen in reticular formation medial to the spinal V tract in all species. An ascending component was found in both the cat and monkey. The identification of some fibers from cranial VII, which ascend and terminate on a prefacial, probably gustatory, portion of the solitary nucleus provides the first confirmation in nerve degeneration studies of Nageotte's results in man. Some ascending fibers also terminated on the most medial cells of the main trigeminal sensory nucleus, a connection not previously described, that probably mediates touch from the auricular region. Another previously unreported connection found only in the monkey was that of some fibers which terminated on a nucleus (paratrigeminal nucleus), dorsolateral to the spinal V tract; this nucleus may represent an oral extension of the lateral cuneate nucleus, and if this is so, the axons terminating in it would be a part of the afferent cerebellar system. Copyright © 1968 The Wistar Institute of Anatomy and Biology