Compartments of the Cavernous Sinus and the Associated Triangles via Endoscopic Endonasal Approach: A Cadaveric Anatomical Study

Introduction: This study aims to identify key anatomical landmarks and describe the endonasal endoscopic anatomy of the cavernous sinus through a cadaveric study. Understanding these anatomical structures and landmarks is crucial for reducing surgical complications. Cavernous sinus lesions are often expansive, obscuring the cavernous portion of the internal carotid artery (ICA), which increases the risk of injury. We examine the superior, inferior, posterior, and lateral portions of the cavernous sinus and their adjacent structures through endoscopic endonasal approaches.

Methods: Anatomical dissections were performed at Baºkaya Lab (University of Wisconsin School of Medicine and Public Health) on freshly injected adult cadavers. We used Karl Storz 0 and 30-degree endoscopes to expose the cavernous sinus and its relevant structures. In five cadavers, stepwise endoscopic expanded transnasal dissections were performed to access the cavernous sinus. The procedure began with a superior and middle turbinectomy, sphenoidectomy, removal of the uncinate process, and bulla ethmoidalis. The posterior wall of the maxillary sinus was then opened, followed by the pterygopalatine fossa. We described the intracavernous sinus triangles in each compartment (superior, inferior, posterior, and lateral) and their contents.

Results: Each compartment of the cavernous sinus has distinct boundaries and dural and neurovascular relationships. The superior compartment consists of the clinoid triangle, oculomotor triangle, and the anterior part of the supratrochlear and infratrochlear triangles. The posterior compartment includes the posterior part of the supratrochlear and infratrochlear triangles, the gulfar segment of the ICA, the abducens nerve, and the inferior hypophyseal artery. The inferior part of the cavernous segment contains the abducens nerve. The lateral compartment comprises the anteromedial and anterolateral triangles, all cavernous cranial nerves, and the inferolateral arterial trunk. Anatomical landmarks were measured at different sites related to the ICA.

Conclusion : Endonasal endoscopic approaches to the cavernous sinus can be divided into distinct compartments. This study attempts to fit all triangles described microscopically into the cavernous sinus compartments. This knowledge will aid surgeons in delineating neurovascular structures more clearly during