Abstract: Objective To study the anatomical and morphological characteristics of the venous spaces involved in surgery via transsphenoidal approach to the cavernous sinus(CS).Methods Ten fixed cadaver heads(six male,four female) with red and blue latex injected in the arteries and veins,respectively,were used to perform the transsphenoidal approach.The anterior wall of the sphenoidal sinus and the floor of sellar turcica were opened as much as possible to expose the dura mater at the sellar floor and the inferior wall of CS,and the location of the anterior and inferior intercavernous sinuses were observed carefully.All the spaces of CS were observed and measured.According to the observations,the venous spaces available for operation were identified and analyzed.Results In all the cadaver heads,4 anterior and 5 inferior intercavernous sinuses were found,with the former locating below the optic protuberance,while the latter situated at the turn of the sellar protuberance at the clival indentation.CS was subdivided into medial space,inferolateral space,and dorsolateral space.Conclusions In transsphenoidal approach,opening of anterior and inferior intercavernous sinus is liable to result in intra-and postoperative venous bleeding,and understanding of the location of the intercavernous sinus and appropriate utilization of these CS may help reduce intraoperative vascular and nerve injury.