G, The floor of the middle fossa has been resected back to the level of the tensor tympani muscle and eustachian tube, and the petrous carotid artery. The nerves exiting the jugular foramen and hypoglossal canal pass laterally between the internal carotid artery and internal jugular vein to reach their end organs. H, The eustachian tube and tensor tympani have been resected and the bone lateral to the foramen ovale removed. This exposes the full length of the petrous carotid. I, The petrous carotid has been reflected forward out of the carotid canal to expose the petrous apex medial to the jugular foramen and lateral wall of the clivus. J, The petrous apex and adjacent part of the clivus medial to the jugular foramen and cochlea have been removed and the dura opened to expose the junction of the vertebral and basilar arteries and the origin of the AICA. (Images courtesy of AL Rhoton, Jr.)