Abstract
This chapter describes the anatomy of the sellar and parasellar regions. It mainly focuses on the anatomy of the cavernous sinus, including its walls, the course of different cranial nerves, and the cavernous/carotid artery. This chapter also describes different parasellar triangles in detail and how surgical approaches can access these triangles and their anatomical structures. In the end, we describe the endoscopic endonasal anatomy of the parasellar region and compartments of the cavernous sinus and compare it to open cranial approaches. © The Author(s), 2023. All rights reserved.