Evaluation of facial nerve and its landmarks in adult temporal bones

Introduction: The aim of this study was to identify variations of different segments of facial nerve in temporal bone. Materials and Methods: In this descriptive study that conducted on drilled bones in the temporal bone center of the Al-Zahra Hospital of Isfahan University of Medical Sciences, the landmarks of facial nerve in temporal bone were identified as separate variables and their distances from outer cortex of temporal bone and Henles spine and distances between different segments of nerve were recorded. Results: In the 50 temporal bones dissected, the distance between the tip of incus short process to the cortex was 14.2±1.96 mm, the distance between the facial recess from the facial nerve to the cortex was 14.5±2.58 mm, the distance between the stylomastoid foramen to the cortex was 20.6±2.49 mm, the distance between the lateral semicircular canal to the cortex was 15.9±2.31 mm and the distance between the sigmoid sinus dome to the cortex was 14.08±2.83 mm. The mean length of tympanic and mastoid segments (2nd and 3rd segments of facial nerve) were 11.35±0.68 mm and 13.28±1.11mm, respectively. Conclusion: The mean lengths of segment of facial nerve and distant of landmarks from outer cortex of temporal bone are partially similar compared to those described in the western literature and text books, but different compared to eastern researches.