A, The roof of the nasal cavity and medial part of the floor of the anterior fossa have been removed to expose the endonasal route to the sellar region. The speculum in the endonasal approach is advanced along the course of the probe. It is advanced in one nostril and passed upward between the nasal septum and the concha to the sphenoid face. The posterior part of the middle concha provides a relative obstacle to exposing the face of the sphenoid in this case, but the concha can be displaced laterally by the blades of the speculum. A prominent concha, like this, may tend to deflect the speculum to the opposite side, unless care is taken to center the speculum blades on each side of the midline vertical crest on the sphenoid face. The posterior ethmoid air cells are positioned anterior to the lateral part of the sphenoid face. The nasal septum, in this case, is deviated to the right. B, The endonasal speculum has been advanced to the sphenoid face in the area below the sphenoid ostia. The septum at this level is formed by the perpendicular plate of the ethmoid. The septum below is formed by the vomer. C, Enlarged view of the speculum blades at the face of the sphenoid. The mucosa is opened in the area below the sphenoid ostia and elevated in a small area so that the blades can be inserted submucosally. D, Opening the speculum separates a small section of the septum from the sphenoid face and displaces the septum to the opposite side. The speculum blades can then be advanced submucosally along the sphenoid face bilaterally. The crest on the sphenoid face formed by the ethmoid perpendicular plate and vomer should be positioned in the midline between the blades of the speculum. (Images courtesy of AL Rhoton, Jr.)