Somatotopic organization of facial nucleus of rabbit. With particular reference to intranuclear representation of perioral branches of the facial nerve.

Somatotopic organization of the facial nucleus was examined in the rabbit by the retrograde HRP (horseradish peroxidase) method; HRP was applied to the peripheral branches of the facial nerve. The facial nucleus is cytoarchitectonically divided into 5 division: the ventromedial, medial, dorsal, lateral and intermediate divisions. The ventromedial division contains neurons supplying the cervical branch. The medial division supplies the anterior auricular branch as well as the posterior auricular branch. The dorsal division is small and contains motoneurons innervating the periorbital regions through the zygomatico-orbital branchlets as well as the anterior auricular branch. Motoneurons innervating the perioral regions are numerous and distributed in the lateral and intermediate division; each of the lateral and intermediate divisions supplies both superior labial and inferior labial branches.