New Aspects of Cavernous Sinus Anatomy

• Published in: Skull Base Vol. 15; no. S 2
• Main Author: Sepehrnia, Abolghassem
• Format: Conference Proceeding Journal Article
• Language: English
• Published: 20.09.2005
• ISSN: 1531-5010; 1532-0065
• DOI: 10.1055/s-2005-916615

Since Ridley in 1695, who placed the ICA against the lateral wall of this sinus and suggested the term “circular sinus,” whereas Winslow in 1732 noted the presence of fibrous trabeculae and applied the term “cavernous,” there has been a controversy about the characteristic of the cavernous sinus (CS). In view of these varied concepts and differing opinions, it was decided to investigate the anatomy of the human CS with special regard to following features: the presence or absence of laminae within the lumen of the CS and, if present, whether they were trabeculae or, in fact, the walls of small veins; the position of the carotid artery and the abducent nerve; the characteristics of the lateral wall. The lateral wall of the CS was consistently found to be formed of two layers, a smooth superficial layer formed by the dura mater and a deep layer containing nerves III, IV, and V1. The two layers are only loosely attached to one another and can be easily separated. In some cases a superficial component of the sinus was found between the layers. The deep layer was less defined than the superficial and was more irregular and variable in its texture and morphological characteristics. It was found to be formed by the sleeves and/or sheath of dura mater accompanying the nerves. It was found as a thin but definitely complete membrane. Due to its transparency it can generally be recognized. To enter the CS, the nerves do not “pierce” the dural walls; instead, the dura forms a sheath around each nerve, a leptomeninseal and dural sheath. The trochlear nerves enter the CS in 75% from above and in 25% from the lower side of the tentorial incisura along its “intradural” course. The entire extent of the carotid artery is within the CS and is covered by a coat of connective tissue lined with endothelium on the side of the venous cavities. Where the artery enters and leaves the sinus, its coat may be joined to the walls of sinus. At this point therefore the artery is firmly fixed to the relatively unyielding walls of the CS. The VIth nerve enters low down through Dorello's canal and courses upward and laterally around the carotid. Aside from the sympathetic nerve, it is the only cranial nerve that is truly within this space. The trabeculae exist in almost all CS specimens either densely or scarcely the lumen of the CS is covered with endothelial cells, but has no vascular wall of its own. The CS has a large nonbranching venous channel, either the broken venous channel with dense trabeculae or the unbroken venous channel with few trabeculae. A distinctive form of connective tissue structure within the CS known as trabeculae bands, etc., was regularly encountered.