A, This oblique cross section extends along the route used for transsphenoidal surgery. The cross section slopes upward and backward from the anterior part of the nasal cavity below to the area in front of the sphenoid sinus and orbital apex above. The roof of the orbit has been removed, leaving some of the floor and lateral wall of the orbit. The maxillary sinuses are exposed below the orbital floor. The conchae extend medially from the lateral nasal wall. The orbital apices are located lateral to the ethmoidal sinuses. The lower part of the nasal septum is formed by the vomer and the upper part is formed by the perpendicular ethmoid plate. B, The cross section has been extended backward to just in front of the sphenoid sinus. The nasal septum deviates to the right. The ethmoidal sinuses are located anterior to the lateral part of the sphenoid sinus. The maxillary sinuses are exposed below the floor of the orbits. C, Enlarged view. The posterior ethmoid air cells are located in front of the upper lateral part of the sphenoid sinus and overlap the lateral margin of the sphenoid ostia. The middle concha, which block the view of the sphenoid face, must be displaced laterally in the transsphenoidal approach. D, The anterior wall of the sphenoid sinus has been removed to expose the sphenoid septi and sella. The carotid prominences are located forward and lateral to the anterior sellar wall. E, The sphenoid septi and osseous wall of the sphenoid sinus and the dural wall of the cavernous sinus have been removed to expose the cavernous sinuses and the dura lining the sella. The cavernous sinus and intracavernous carotid are exposed lateral to the sella. The lamina terminalis is exposed above the chiasm. F, Enlarged view. The dura lining the sella has been removed to expose the pituitary gland, the intracavernous carotid, and the cavernous sinuses. The optic canals are exposed in the superolateral part of the sphenoid sinus. (Images courtesy of AL Rhoton, Jr.)