Endoscopic Approach to the Middle Clivus. G, 45-degree endoscope directed laterally to view the proximal part of the facial nerve in the cerebellopontine angle. The yellow circle in the inset shows the endoscopic visual field. The facial nerve courses in the lower lateral part of the middle clival area. H, Closer view with the 45-degree endoscope. The endoscope has been introduced at the level of the lower clivus and directed superior. The root exit zone of the facial nerve can be observed more clearly (arrow) than in G because the root exit zone is located in the supraolivary fossette, a shallow depression at the lateral edge of the pontomedullary sulcus. (Images courtesy of AL Rhoton, Jr.)