Inferior petrosal sinus
Sinus petrosus inferior
A paired dural venous sinus on the skull base, carrying blood from the cavernous sinus to the internal jugular vein.
At a glance
- English
- Inferior petrosal sinus
- Latin (TA2)
- Sinus petrosus inferior
- System
- Vein
- Region
- Head
- Side
- Paired, left and right
About the inferior petrosal sinus
Each inferior petrosal sinus is a narrow venous channel in the dura mater of the posterior cranial fossa. It lies in the inferior petrosal groove, the furrow along the line where the petrous temporal bone meets the clivus of the occipital bone. There is one on each side.
The sinus starts at the back of the cavernous sinus, just below and behind it, and runs backwards and down along the groove. It passes through the front part of the jugular foramen, in the compartment that also carries the glossopharyngeal nerve, and ends by opening into the internal jugular vein just below the skull, near its superior bulb. Its partner, the superior petrosal sinus, runs higher on the petrous bone and drains into the transverse sinus instead.
Along its length the sinus takes in the labyrinthine veins from the inner ear and veins from the medulla oblongata, the pons and the under surface of the cerebellum. It is also linked across the clivus with the sinus of the other side by the basilar plexus, which in turn connects with the venous plexus in the vertebral canal. It is thus one of the main exits for blood leaving the cavernous sinus.
Clinically, the sinus gives access to the cavernous sinus from below. Catheters passed up from the internal jugular vein can enter it to treat arteriovenous fistulas of the cavernous sinus. Sampling blood from both inferior petrosal sinuses at the same time is also a standard test to find out whether excess ACTH in Cushing syndrome comes from the pituitary gland.
Course and drainage
- Begins at
- Arises from the posterior part of the cavernous sinus.
- Drains into
- Leaves the skull by the front compartment of the jugular foramen and ends in the internal jugular vein just below the skull.
- Drains
- Drains the cavernous sinus, the inner ear through labyrinthine veins, and veins of the medulla, pons and lower cerebellum.
Anthromica
See the inferior petrosal 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.
