[Facial nerve anatomy in neonates. Second and third parts : Surgical applications].

Anatomy of the second and third parts of the facial nerve in the neonatal period was studied by dissection of 15 cadavers. A particular feature was the shortness of the 3rd portion, due to the absence of development of the mastoid. The facial nerve lies an average of 2.4 mm below the antral floor, close to the vertical portion of its posterior border. The stylomastoid foramen is situated on the external surface of the mastoid rudiment, masked by the anterior border of the digastric muscle. Though surgery is rarely indicated, the characteristic features of facial nerve anatomy in neonates should be known.