Endoscopic endonasal approach through the left nostril. The nasoseptal flap has been harvested. Its pedicle, formed by branches of the posterior nasal artery, comes from the pterygopalatine fossa. The pedicle of the flap can be fully mobilized after wide opening of the pterygopalatine fossa. The left sphenoid sinus is now open. (Image courtesy of JC Fernandez-Miranda)