ObjectiveTo provide anatomic data for accurately locating the important structures of sellar area and preventing injury during endoscopic extended transsphenoidal approach to the sellar area. MethodsThe extended transsphenoidal approach was employed in twenty cadavers via endoscope, and the posterior wall of sphenoid sinus was divided into different parts for localizing sella turcica, carotid protuberance and optic canal. Important structures were observed and measured under microscope. ResultsThe posterior wall of sphenoid sinus was divided into five parts according to the four lines along the two sides of the two carotid protuberances. The depths of the sella turcica in the tuberculum sellae, anterior wall of sella turcica and sellar floor were (2.20±0.19 [0.636.90]) mm, (0.71±0.06 [0.362.78]) mm, and (0.94±0.18 [0.232.81]) mm, respectively. The transverse diameter, sagittal diameter and coronal diameter of pituitary gland were (14.72±1.07 [10.9218.38]) mm, (10.13±0.92[9.3712.51]) mm and (5.13±0.74 (2.377.91]) mm, respectively. ConclusionThe five parts of the posterior wall of sphenoid sinus in this study can facilitate the localization of important structures in the sellar area during the extended transsphenoidal approach to sellar area via endoscope, so as to prevent iatrogenic injury of vital structures in the sellar area.