Transpterygoid approach, step by step. The floor of the sphenoid sinus and basopharyngeal fascia have been removed to expose the middle and lower clivus and to completely skeletonize the pterygosphenoidal fissure. The pterygosphenoidal fissure has a mediolateral, anteroposterior,and inferosuperior trajectory that ends up at the inferomedial aspect of the foramen lacerum. Vidian nerve and pterygosphenoidal fissure converge at an approximate 45-degree angle on the lower aspect of the foramen lacerum. The pterygoid tubercle, still present on the left side, has been partially removed on the right side to expose the anterior wall of the lower aspect of the foramen lacerum. The medial wall of the foramen lacerum is formed by sphenoid bone that covers the foramen lacerum ICA segment and extends posteriorly to the petroclival fissure, located just behind the ICA. (Image courtesy of JC Fernandez-Miranda)