Tuesday, 4 November 2014

Cavernous sinuses

The cavernous sinus is one of the dural venous sinuses. It is located on either side of the pituitary fossa and body of the sphenoid bone between the endosteal and visceral layers of the dura.

Vascular connections
It receives blood from the
inferior ophthalmic vein (or a branch thereof)
superficial middle cerebral vein
inferior cerebral veins
sphenoparietal sinus
and occasionally
central retinal vein
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 to the pterygoid plexus
emissary viens passing through the:
sphenoidal foramen
foramen ovale
foramen lacerum
Depending on relative pressures the superior ophthalmic veins either drain to or drain the cavernous sinus.

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

The cavernous sinus transmits multiple cranial nerves to the superior orbital fissure and foramen ovale. These are:
In the lateral wall from superior to inferior:
oculomotor nerve (CN III)
trochlear nerve (CN IV)
trigeminal nerve (CN V) ophthalmic and maxillary divisions.
Traversing the sinus lateral to the ICA
abducents nerve (CN VI)
These can be remembered with the mnemonic OTOM CAT.

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.

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