E, Additional bone has been removed around the internal acoustic meatus and the dura opened to expose the facial and vestibulocochlear nerves. F, The exposure has been extended lateral to the internal acoustic meatus. The tegmen has been opened to expose the head of the incus in the epitympanic area. The osseous capsule of the labyrinth has been opened to expose the semicircular canals. The presigmoid dura behind the labyrinth has been exposed and opened. G, A translabyrinthine approach directed through the middle fossa has been completed by removing the semicircular canals and vestibule. The dura has been opened to give an exposure through the middle fossa similar to that seen with the presigmoid approach. The labyrinthine, tympanic, and mastoid segments of the facial nerve have been exposed. H, This extended middle fossa exposure extends from the lateral wall of the cavernous sinus, across the trigeminal nerve to the area lateral to the internal acoustic meatus, and provides wide access to the anterior part of the posterior fossa. (Images courtesy of AL Rhoton, Jr.)