Abstract:ObjectiveTo develop an endoscopic anatomic and surgical model of pterygopalatine fossa, infratemporal fossa via endonasalmaxillary approach, and to establish endoscopic methodology for localization of internal carotid artery in the parapharyngeal space.Methods100 normal adult heads (200 sides) were scanned by CT and reconstructed threedimensionally, and their anatomical data (such as distance from superior margin of choana narium to foreman lacerum) were measured and recorded. 12 pterygopalatine and infratemporal fossae were dissected in 6 adult cadaver heads in accordance with institutional protocols. Both the pterygopalatine and infratemporal fossae were accessed via transpterygoid approach, which included medial maxillectomy. Location of the internal carotid artery in parapharyngeal space was highlighted.ResultsThe mean distances from superior margin of choana narium to foreman lacerum, outer foreman of carotid artery and jugular foreman were 13.65 mm, 31.81 mm, 32.5 mm respectively, while the related angles were 72.0°,57.6°,54.1°. The alar spine of sphenoid bone and the Eustachian tube were the most important landmarks for the localization of the outer foreman of carotid artery, and the mean distance between them was 5.92(4.90-6.94) mm.ConclusionThe posterior margin of vomer, pterygoid process and alar spine of sphenoid bone, fossa ovale and styloid process are important marks in dissection of internal carotid artery related nasopharyngealskull base. The alar spine of sphenoid bone and the bone portion of the Eustachian tube are landmarks of anterior border of the outer foreman of carotid artery. These landmarks are essential to prevent surgical damage of the internal carotid artery.