The clinical significance of the branching pattern of the facial nerve in Malaysian subjects

Fine dissection was carried out in 79 facial halves from formalin fixed Malaysian adult cadavers of various races, to trace the extracranial part of the facial nerve and its peripheral branches. The facial nerve trunk, after leaving the stylomastoid foramen was located at a depth of 1 to 2 cm from the skin in the vagino-mastoid angle. It bifurcates at the posterior border of the ramus of the mandible and in 3.8% trifurcation was found. Mean distance of bifurcation from the angle of the mandible was 28.06 mm and 81.0% were within the range of 21 to 35 mm. The branching patterns were classified into six types, and the frequency of occurrence was type I 11.39%, type II 15.9%, type III 34.18%, type IV 18.98%, type V 7.59% and type VI 12.67%. Type I, a classical text book pattern was found to be one of the least common patterns. There is no significant difference in percentage of each type between the present study and that of Koreans, though some differences with Caucasians were noted in three uncommon types. The frontal branch could be outlined between the two diverging lines from the earlobe to the lateral ends of the eyebrow and the highest frontal crease. Posterior to the facial artery, the mandibular branch was seen passing below the inferior border of the mandible in 20%; anterior to the artery, this nerve divides into one to four branches. In almost all the cases, branches to the mentalis and the depressor labii inferioris muscles and infrequently branches to the depressor angular oris were seen below the inferior border of the mandible.(ABSTRACT TRUNCATED AT 250 WORDS)