Microdissection of petroclival region in temporal base transpetrosai transtentorial approach

Objective: To explore the important anatomical structures of temporal bone and petroclival region in temporal base transpetrosal transtentorial approach. Methods: Ten dried skulls for a total of 20 sides were used to explore the morphometric relationships. The anatomical relationships and distance among the correlated structures in temporal base transpetrosal transtentorial approach were studied and measured. Results: The distance between the anterior border of the external auditory foramen and the root of zygoma, superior border and the bone tuberositas above external auditory foramen, posterior border and the anterior angle of parietomastoid sutures, were 13.80±1.33mm, 6.18±1.20mm,and 26.18±3.90mm; the distance between the foramen lacerum and the petrous apex impression by trigeminal nerve was 6.62±1.66mm; the distance between the hiatus canalis facialis and petrous ridge was 11.79±1.00mm. The location of the internal auditory canal was on the angular bisector of the angle form by the arcuate eminence and the nervus petrosus superficialis major. The distance from the common crus to posterior border of the internal auditory foramen was 9.30±0.58mm; from cochlea to petrous ridge was 8.00±1.07mm; from the posterior semicircular canal to the petrous ridge was 4.30±0.60mm; and from the internal carotid canal to the petrous ridge was 10.47±1.34mm. Conclusions: The eminence part of the mastoid superior ridge can indicate the STP. The dura of the front petrous bone should be dissect within the field formed by the hiatus canalis facialis. The petrous bone can be divided into three parts: the medial、intermediate and lateral part, and the safety resecting field is different in each part.