Endoscopic endonasal approach through the left nostril. The uncinate process has been partially removed to access the maxillary sinus. The posterior wall of the maxillary sinus has been partially opened to expose the pterygopalatine fossa and increase the opening of the sphenopalatine foramen. The posterior nasal artery is a branch of the sphenopalatine artery and runs from the pterygopalatine fossa to the nasal septum passing through the sphenopalatine foramen. Important landmarks for harvesting the nasoseptal flap are inferior aspect of the sphenoid ostium superiorly and the superior aspect of the choana inferiorly. The bulla ethmoidalis has been totally removed. (Image courtesy of JC Fernandez-Miranda)