The cavernous sinuses are paired dural venous sinuses.
The cavernous sinus is located on either side of the pituitary fossa and body of the sphenoid bone between the endosteal and meningeal layers of the dura. 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.
- roof: fold of dura mater attached to the anterior and middle clinoid processes
- anterior wall: medial end of the superior orbital fissure
- posterior wall: petrous apex
- medial wall: endosteum overlying the body of the sphenoid bone
- lateral wall: dura mater from the ridge of the roof to the floor of the middle cranial fossa
- floor: endosteum overlying the base of the greater wing of the sphenoid bone
- superiorly: middle cerebral artery, optic chiasm
- anteriorly: apex of the orbit
- posteriorly: cerebral peduncle
- medially: pituitary fossa, pituitary gland
- laterally: temporal lobe (medial surface), Meckel's cave (posteroinferiorly)
- inferiorly: sphenoid sinus
It receives venous blood from:
- inferior and superior ophthalmic veins
- intercavernous sinus
- sphenoparietal sinus
- superficial middle cerebral vein
- central retinal vein
- a frontal tributary of the middle meningeal vein
Drainage of the cavernous sinus is via:
- superior petrosal sinus to the transverse sinus
- inferior petrosal sinus directly to the jugular bulb
- venous plexus on the internal carotid artery (ICA) to the clival (basilar) venous plexuses
- emissary veins passing through the
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.
- in the lateral wall from superior to inferior
- traversing the sinus
The ICA 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 .