A, The section of the facial structures extends across the nasal cavity, superior and middle turbinates, maxillary sinuses, the orbits near the apex, and the ethmoid sinuses in front of the sphenoid sinus. The zygomatic and infraorbital nerves arise from the mandibular nerve in the pterygopalatine fossa, which is located behind the posterior wall of the maxillary sinus. B, The turbinates and posterior ethmoid air cells have been removed to expose the vomer and the anterior face of the sphenoid sinus. The nasolacrimal duct descends along the lateral wall of the nasal cavity and opens below the inferior turbinate into the inferior meatus. C, The anterior face of the sphenoid sinus has been removed to expose the multiseptated sphenoid sinus and the anterior wall of the sella. The bony prominences over the optic canals are situated in the superolateral margins of the sphenoid sinus. D, The anterior wall of the sella and the lateral walls of the sphenoid sinus have been removed to expose the petrous and cavernous carotid and the pituitary gland. The posterior wall of the sphenoid sinus, which forms the anterior surface of the upper clivus, has been preserved. (Images courtesy of AL Rhoton, Jr.)