A, The scalp incision is positioned so that a frontotemporal craniotomy can be completed. The operation is often completed with an incision that extends downward only to the level of the tragus. However, it can be extended if a neck dissection is needed. The scalp flap has been reflected forward, taking care to protect the branches of the facial nerve. B, The temporalis muscle has been refracted forward and the craniotomy completed. The mandibular condyle and fossa and a portion of the zygomatic arch were removed in a single piece, as shown in the insert, and the middle fossa floor removed. C, Exposure after removal of the middle fossa floor lateral to the foramen ovale and before resection of the tensor tympani muscle. The lower orifice of the carotid canal is located in front of the jugular foramen. The eustachian tube, which passes across the front of the petrous carotid, has been opened. D, The tensor tympani and eustachian tube have been resected to expose the horizontal segment of the petrous carotid. E, The internal carotid artery has been reflected forward and the petrous apex drilled to expose the posterior fossa dura and the inferior petrosal sinus coursing along the petroclival fissure. F, The dura facing the petrous apex has been opened and the vertebral arteries and AICA exposed. This exposure is directed through the petrous apex medial to the cochlea and jugular foramen and does not risk loss of facial nerve function or hearing, as do the approaches directed through the petrous apex that require facial nerve transposition and resection of the labyrinth. (Images courtesy of AL Rhoton, Jr.)