Posterior intercavernous sinus
Sinus intercavernosus posterior
A small dural venous sinus crossing the midline behind the pituitary gland, joining the two cavernous sinuses.
At a glance
- English
- Posterior intercavernous sinus
- Latin (TA2)
- Sinus intercavernosus posterior
- System
- Vein
- Region
- Head
- Side
- Single, on the midline
About the posterior intercavernous sinus
The posterior intercavernous sinus is a short cross channel within the dura mater of the middle cranial fossa. It runs across the midline behind the hypophysis, the pituitary gland, in the back edge of the diaphragma sellae, close to the dorsum sellae. Each end opens into the cavernous sinus of that side.
It is matched in front of the gland by the anterior intercavernous sinus. The two cross channels, with the cavernous sinuses on either side, make up the circular sinus, a ring of venous blood around the pituitary and its stalk. The posterior sinus is generally the smaller of the two and is more often absent. Behind it, venous channels on the clivus form the basilar plexus, which joins the inferior petrosal sinuses and reaches down to the veins of the vertebral canal.
Functionally, the sinus lets blood pass between the cavernous sinuses so that pressure stays balanced and either side can drain when the other is obstructed. Blood leaving the back of the pituitary region and the dorsum sellae drains into it, and from the cavernous sinuses the flow continues backwards through the superior and inferior petrosal sinuses.
Because the circular sinus joins the right and left cavernous sinuses, infection or thrombosis that begins on one side can quickly involve the other, which is why cavernous sinus thrombosis often ends up affecting both eyes. In transsphenoidal pituitary surgery the intercavernous sinuses can be a source of venous bleeding when the dura of the sella is opened, although the posterior channel is less often in the way than the anterior one.
Course and drainage
- Begins at
- Arises from one cavernous sinus behind the pituitary gland.
- Drains into
- Opens into the opposite cavernous sinus, completing the back of the circular sinus.
- Drains
- Links the two cavernous sinuses and drains veins from behind the hypophysis and the dorsum sellae.
Anthromica
See the posterior intercavernous sinus where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
