A, The upper part of the nasal cavity is separated from the orbits by the ethmoidal sinuses. The lower part of the nasal cavity is bounded laterally by the maxillary sinuses. The middle concha projects medially from the lateral nasal wall at the junction of the roof of the maxillary and ethmoidal sinuses. The posterior ethmoid air cells are located in front of the lateral part of the face of the sphenoid sinus. B, The middle and inferior nasal conchae on the left side and the nasal septum and the posterior ethmoidal sinuses on both sides have been removed to expose the posterior nasopharyngeal wall, the anterior aspect of the sphenoid body, and the sphenoid ostia. The posterior ethmoid air cells overlap the lateral margin of the sphenoid ostia. C, The anterior wall of the sphenoid sinus has been opened and the sphenoid septa has been removed to expose the anterior sellar wall in the midline and the prominences over the optic canal and carotid arteries in the lateral walls of this well-pneumatized sphenoid sinus. The medial part of the posterior wall of the left maxillary sinus has been removed to expose branches of the maxillary artery in the pterygopalatine fossa. The opticocarotid recesses extend laterally between the prominences over the carotid arteries and optic nerves. D, The pituitary gland, intracavernous carotids, optic nerves, ophthalmic arteries, and cavernous sinuses have been exposed by removing the bone of the sinus wall. The inferolateral trunk passes above and lateral to the abducens nerve. The shortest distance between the paired carotid arteries is usually located just below the tuberculum selle. A capsular artery arises from the intercavernous carotid and passes upward and medially. E, Oblique view. The bony prominences overlying the optic canal, superior orbital fissure, intracavernous carotid artery, and the maxillary nerve are exposed in the lateral wall of the sphenoid sinus. The bony depression between the carotid prominence and the optic canal, the opticocarotid recess, extends into the medial end of the optic strut. The broad round prominence below the opticocarotid recess is produced by the structures passing through the superior orbital fissure. F, Oblique view. The pituitary gland, intracavernous carotid artery, ophthalmic artery, and optic, ophthalmic, maxillary, oculomotor, and abducens nerves have been exposed. The abducens nerve courses medial to the ophthalmic nerve. (Images courtesy of AL Rhoton, Jr.)