G, The lower clivus has been opened to expose both vertebral arteries, lower part of the basilar artery, right PICA, left AICA, and the abducens and hypoglossal nerves. H, The anterior arch of C1 has been removed to expose the odontoid process. I, A degloving subperiosteal dissection exposes the anterior face of the maxilla and the lower part of the anterior piriform aperture. J, The transverse maxillary (LeFort I) osteotomy extends through the maxillary sinus above the apex of the teeth and below the infraorbital canals. (Images courtesy of AL Rhoton, Jr.)