[The extended middle cranial fossa approach: a morphometric analysis].

The extended middle cranial fossa (EMCF) approach calls for removal of the petrous bone from its subtemporal surface in order to well expose the internal auditory canal (IAC) and the posterior fossa dura (PDF) around its meatus, safeguarding, at the same time, all the important, closely related, anatomical structures (the Gasserian ganglion (GG) and its third trigeminal division, the internal carotid artery (ICA), the cochlea, the posterior labyrinth, the superior petrosal sinus (SPS), the inferior petrosal sinus (IPS) and the jugular bulb (JB). The middle meningeal artery, on the other hand, could be divided when necessary. We dissected 25 temporal bones preserved in formaldehyde and those of five cadavers in order to define the limits of this approach. Measurements were taken so as to establish the limits of the approach as well as to determine the most appropriate angles and distances in working in this area. As previously suggested by the Senior Author (MS), we found it safer to start working medially in order to identify the IAC and then to extend the dissection laterally. The most constant angle proved to be that between the IAC and the SPS. The distances and areas found appear to be highly variable and difficult to rely upon. A thorough knowledge of this anatomy is of most importance for the surgeon who intends to use this approach.