Surgical Landmarks for the Internal Carotid Artery in Endoscopic Endonasal Approaches. G–I, 45-degree view directed at the right side. The levator veil palatine muscle is identified at its attachment to the palatine aponeurosis medially and followed to its origin laterally at the rough quadrilateral surface and the anterior crest of the petrous bone. Detaching this muscle from its origin at the inferior petrous bone exposes the entrance of the parapharyngeal ICA to the ICA canal. J, 0-degree panoramic view. A sphenoidectomy and bilateral anterior and posterior ethmoidectomies have been performed. The maxillary sinuses are opened bilaterally, but the posterior wall of the right sinus remains intact. The right palatovaginal canal (asterisk) is identified. The pterygoid wedge (triangle) is depicted on the right side. The pterygoid wedge is a beak-shaped area that marks the site where the medial pterygoid plate meets the floor of the sphenoid sinus. K–M, 30-degree view directed at the left side. The posterior and medial aspects of the maxilla have been drilled and the pterygopalatine ganglion exposed in the pterygopalatine fossa. The greater palatine canal formed by the articulation of the vertical groove on the maxillary surface of the palatine bone with the maxilla itself has been opened. A transpterygoid approach where the vidian canal has been drilled has also been completed. The vidian nerve, the union of the greater superficial petrosal, and the deep petrosal nerves are identified. L, The vidian nerve is followed posteriorly from the pterygopalatine ganglion toward the lateral aspect of foramen lacerum; hence, we use it as an important landmark for the distal aspect of the petrous ICA. (Images courtesy of AL Rhoton, Jr.)