Transpterygoid approach, step-by-step. The palatosphenoidal artery has been transected. This is the key step to perform a subperiosteal dissection along the pterygoid process, from medial to lateral, and accurately find theanterior opening of the vidian canal. The palatosphenoidal canal is at the same level of the vidian canal. Once the vidian canal has been identified, the drilling can then take two routes: supravidian and infravidian. The transpterygoid supravidian approach is perfomed by drilling the pterygoid process between vidian canal and foramen rotundum to access the lateral recess of the sphenoid sinus and the middle cranial fossa floor. The transpterygoid infravidian approach is performed by drilling the pterygoid process and medial pterygoid plate between vidian canal and Eustachian tube to access the ventral petroclival fissure, inferior petrous apex, and ventral jugular foramen. Both routes, supra and infravidian, converge at the foramen lacerum. (Image courtesy of JC Fernandez-Miranda)