Surgical anatomy of the facial nerve in Chinese mastoids.

Since racial differences in mastoid morphology exist, there may be racial differences in the surgical anatomy of the facial nerve in the mastoid. Thirty Chinese adult temporal bones were dissected. The facial nerve in the mastoid coursed vertically (60.0%), anteriorly (33.3%) and posteriorly (6.7%) in the sagittal plane. In the coronal plane, it coursed vertically (46.7%) and laterally (53.3%). The chorda tympani was found to have extratemporal origin in 53.3% and for the rest, the distance of its origin from the stylomastoid foramen averaged 3.17 mm (range 0.5-6.0 mm). The mean dimension of the extended facial recess was 4.40 mm (range 3.0-6.0 mm). The facial nerve was at a mean of 3.15 mm (range 2.0-5.0 mm) posterior to the most posterior point of the tympanic annulus and partially crossed the tympanic annulus from medial to lateral at this point. In conclusion, the typical surgical anatomy of the mastoid facial nerve as described in the Western literature may not apply to the Chinese.