Histomorphometric Characteristics of the Facial Nerve

Kwak, Hyun Ho; Koo, Byung Chan; Hu, Kyung Seok; Kim, Gyoo Cheon; Park, Bong Soo; Kim, Hee Jin

Abstract

With the development of microsurgery, autogenous nerve grafting is being used widely in the treatment of the injured facial nerve. To use a donor graft for repair of the facial nerve, fascicular area and fascicular number should be considered in the selection of the donor site. This study demonstrated a detailed morphologic description of the facial nerve, including a microscopic assessment of nerve size and shape, and fascicular number and diameters. 40 embalmed hemi-sectioned head specimens from Korean adult cadavers were dissected to identify the facial nerve branches and nerve samples for histologic examination were cut from the anterior margin of the parotid gland.At the border of the parotid gland, the facial nerve specimens were found to have an average of 11 branches (ranging from 8 to 16). The branches were distributed among the five distinct branches, the buccal branch had the greatest number of branches (3.47), and the zygomatic branch had the largest diameters (0.93 mm). The number of fascicles varied from one to 9 over the course of the nerve, the trunk had the greatest number of fascicles (4.36), and averages indicated a tendency for fascicular numbers to decrease distally, from trunk (4.36) to upper division (3.72) to lower division (3.60) to marginal mandibular branch (2.37). The total fascicular area was averaging 2.72 mm2, 1.88 mm2, and 1.04 mm2 at trunk, upper division, and lower division, respectively. However no significant differences of the fascicular diameter could be shown between five branches. This results of detailed facial nerve microanatomy should help in the treatment of the injured facial nerve.