Anatomical and Histological Studies on Extracranial Facial Nerve of Rat

Objective To investigate the conformation,course,and branches of the rat's facial nerve so as to provide the basic data for the experimental researches.Methods The facial nerve and its branches were exposed by dissecting and the length and outside diameter of the various branches were measured,and their conformations were observed by microscopy after modified trichrome staining.Results The facial nerve trunk of rat came out of stylomastoid foramen,and then went forward along the masseteric surface and was divided into temporal branch,zygomatic branch,buccal branch,marginal mandibular branch,and cervical branch.These branches ended to the corresponding facial muscles.The length of temporal branch,zygomatic branch,buccal branch,marginal mandibular branch,and cervical branch was 10.59 mm±0.34 mm,15.48 mm±1.86 mm,26.18 mm±1.37 mm,26.31 mm±1.32 mm,and 17.54 mm±0.75 mm respectively,and their outside diameter of the middle point was 0.56 mm±0.12 mm,0.70 mm±0.08 mm,1.01 mm±0.28 mm,0.91 mm±0.20 mm,and 0.64 mm±0.15mm respectively.In light microscope,they were characterized by green and intact endoneurium,two or three bundles,regular order of nerve fibers,small axons located in the center of the fibers,red Schwann's sheath,and hyacinthine Schwann's nucleus.Conclusion The buccal branch and marginal mandibular branch of the rat's facial nerve are suitable for the experiment developing the model of nerve injury and regeneration.