A microdissection study of the facial nerve at the labyrinthine and tympanic segments in adults.

OBJECTIVES To determine the relationship in detail between the tympanic and the labyrinthine segments of the facial nerve and the relationship between the bony structures and the neighboring nerve. MATERIALS AND METHODS Measurement of the length of the segment of the facial nerve within the internal auditory canal and the lengths of the labyrinthine and tympanic segments were made on fourteen temporal bones collected from eight fresh cadavers. RESULTS The minimum distance between the point where the facial nerve leaves the internal auditory canal and the tympanic segment was measured as 4.71+/-0.54 mm. The angle between the labyrinthine and the tympanic segments at the geniculate ganglion was measured as 73 degrees 85' +/-10 degrees 89'. The angle between the labyrinthine and the superior vestibular nerve were measured as 34 degrees 35' +/-5 degrees 51'. CONCLUSION We believe that the results of our measurements will help the surgeons to minimize the complications who work in this particular anatomic area.