Transtemporal approaches exposing the petroclival region require extensive drilling of the petrous bone. This is only possible with an understanding of the three dimensional anatomy of the temporal bone and the cranial base. The purpose of this study is to review the topographic anatomy of the petrous bone and peripetrous region, with emphasis on the relationships critical to the lateral approaches for posterior and lateral skull base. To understand the surgical anatomy and the cranial base approaches to this area, 8 cadaveric heads and 76 dry skulls were studied. Cadaveric dissections were performed, and morphometric data from measurements of the relationships of the surface landmarks in the petroclival region were provided. The results and the observations could be useful to understand the anatomy better, and to estimate the degree and direction of a safe bony removal for the most radical transpetrosal surgery.