Cavernous sinus

Last revised by Craig Hacking on 18 Oct 2022

The cavernous sinuses are paired dural venous sinuses

Gross anatomy

The cavernous sinus is located on either side of the pituitary fossa and body of the sphenoid bone. It is most easily thought of as existing between the endosteal and meningeal layers of the dura although some additional complexity is present 5. It spans from the apex of the orbit to the apex of the petrous temporal bone. Unlike other dural venous sinuses, it is divided by numerous fibrous septa into a series of small caves, which is where its name is derived from. The normal lateral wall should be either straight or concave. 

Dural anatomy

The lateral wall of the cavernous sinus is primarily formed by the continuation of the meningeal layer of the dura, flowing medially up from the floor of the middle cranial fossa, over the cavernous sinus, to the clinoid processes before forming the diaphragma sella. From here, the meningeal layer passes downwards to surround the pituitary gland, thus forming the medial wall of the cavernous sinus. In contrast, the floor of the cavernous sinus is formed by the endosteal layer of the meninges (actually just periosteum) that covers the sphenoid bone and passes medially across the midline below the pituitary gland, separated from the aforementioned meningeal layer by the intercavernous sinus 5

The nerves in the lateral wall of the cavernous sinus are surrounded by thin connective tissue and thus, the lateral wall of the cavernous sinus has two layers; a thick meningeal layer and a much thinner translucent layer surrounding the cranial nerves 5,6. This thin layer is variably described as being meningeal in origin 6, or continuous with the endosteal layer 5

Vascular connections

It receives venous blood from:

Drainage of the cavernous sinus is via:

Depending on relative pressures the superior ophthalmic veins either drain to or from the cavernous sinus.

Additionally, the cavernous sinuses connect to each other via the intercavernous sinuses.


These can be remembered with the mnemonic O TOM CAT.


The cavernous sinus transmits multiple cranial nerves to the superior orbital fissure and foramen rotundum. These are:


The internal carotid artery enters the posterior inferior aspect of the sinus and bends upon itself as the carotid siphon (cavernous segment - C4). Two branches arise from this segment: meningohypophyseal trunk and inferolateral trunk.

The artery is surrounded by a plexus of sympathetic nerves from the superior cervical ganglion.


Fatty deposits may be present within the cavernous sinus, especially in obese patients or in those who are taking corticosteroids 3.

Related pathology

ADVERTISEMENT: Supporters see fewer/no ads

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.