Transpterygoid approach, step-by-step. The medial wall of the maxillary sinus has been removed to enter the sinus and expose its posterior wall. The prominence for the infraorbital nerve can be identified at the medial aspect of the roof of the maxillary sinus. The sphenopalatine foramen is located between the sphenoidal process and the orbital process of the palatine bone. The palatosphenoidal artery and canal are not exposed, because they are covered by the sphenoid process. The floor of the sphenoid sinus serves as a landmark for the estimated location of the vidian canal. (Image courtesy of JC Fernandez-Miranda)