[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) › Petrosal sinuses [Cardiovascular system](https://durgical.com/en/anatomy/system/cardiovascular-system/) · [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) # Petrosal sinuses The petrosal sinuses are small vein channels along the skull base, near the ear bone, that drain the cavernous sinus toward the neck veins. Official name: Superior petrosal sinus [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=head_neck&select=petrosal_sinuses&side=r) Opens in the Durgical app, no sign-up needed. ## What it is Smaller sinuses along the petrous bone and the back of the skull base. ## What it does Drain the cavernous sinus and the skull base. ## Key points - Superior petrosal sinus: in the attached edge of the tentorium along the petrous ridge, from the cavernous sinus to the junction of the [transverse sinus](https://durgical.com/en/anatomy/transverse-sinus/) and [sigmoid sinus](https://durgical.com/en/anatomy/sigmoid-sinus/) - Inferior petrosal sinus: in the groove between the petrous [temporal bone](https://durgical.com/en/anatomy/temporal-bone/) and the clivus, from the cavernous sinus through the front of the jugular foramen to the [internal jugular vein](https://durgical.com/en/anatomy/internal-jugular-vein/) - Inferior petrosal sinus sampling: blood from both sides is tested for pituitary ACTH to confirm Cushing disease and suggest the tumour's side ## Key facts **Drains** Cavernous sinus, skull base **Into** Superior -> transverse/sigmoid; inferior -> internal jugular ## Relations **Course** Both leave the back of the [cavernous sinus](https://durgical.com/en/anatomy/cavernous-sinus/): the superior runs back along the petrous ridge to the transverse–sigmoid junction; the inferior runs down and back to the [jugular foramen](https://durgical.com/en/anatomy/jugular-foramen/) **Above** Above the superior sinus: the attached edge of the [tentorium cerebelli](https://durgical.com/en/anatomy/tentorium-cerebelli/) and the [temporal lobe](https://durgical.com/en/anatomy/middle-temporal-gyrus/) **Below** The [trigeminal nerve](https://durgical.com/en/anatomy/trigeminal-nerve/) passes beneath the superior sinus at the petrous apex into Meckel's cave; the [abducens nerve](https://durgical.com/en/anatomy/abducens-nerve/) runs close to the inferior sinus in Dorello canal **Medial** Clivus with the basilar venous plexus, which links the two sides ## How to find it Neither can be felt. The superior sinus is seen along the petrous ridge in the retrosigmoid approach, where the petrosal vein joins it; the inferior sinus is reached by a catheter passed from the [femoral vein](https://durgical.com/en/anatomy/femoral-vein/) up the internal jugular vein for sampling. ## On imaging MR or CT venography shows the superior sinus along the petrous ridge and the inferior sinus in the groove between the petrous bone and the clivus. In ACTH-dependent Cushing syndrome, inferior petrosal sinus sampling by catheter compares ACTH from both sinuses with peripheral blood to confirm a pituitary source. They also take part in cavernous sinus thrombosis and dural fistulas. ## Clinical notes - Petrous apex infection from otitis media can affect the abducens nerve nearby: Gradenigo syndrome (ear discharge, pain around the eye, [lateral rectus](https://durgical.com/en/anatomy/lateral-rectus-muscle/) palsy) - The petrosal vein (of Dandy) drains the [cerebellum](https://durgical.com/en/anatomy/anterior-quadrangular-lobule/) and brainstem into the superior petrosal sinus; it is met in cerebellopontine angle surgery such as microvascular decompression for trigeminal neuralgia - Thrombosis of the cavernous sinus can spread along them toward the sigmoid sinus and internal jugular vein ## Anatomical variants - The inferior petrosal sinus joins the internal jugular vein in varying ways, sometimes outside the skull or into the vertebral venous plexus, which can make catheter sampling difficult ## Development The superior petrosal sinus is the old drainage trunk of the middle embryonic dural plexus, which turns to carry blood from the cavernous sinus to the transverse sinus; the inferior petrosal sinus appears later. ## Test yourself Think of the answer, then tap the question to see it. ## Where do the superior and inferior petrosal sinuses drain the cavernous sinus to? The superior petrosal sinus to the junction of the transverse and sigmoid sinuses; the inferior petrosal sinus to the internal jugular vein through the jugular foramen. ## What is inferior petrosal sinus sampling used for? Blood from both sides is tested for pituitary ACTH to confirm Cushing disease and suggest the tumour's side. ## What is Gradenigo syndrome? Petrous apex infection from otitis media affecting the nearby abducens nerve: ear discharge, pain around the eye and lateral rectus palsy. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/superior-petrosal-sinus/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** sinus petrosus superior TA2 4850 **Official Spanish (DeCS)** Senos petrosos y occipital DeCS D003392 **English (TA2)** Superior petrosal sinus Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=3408&filter=ths_termall&q=Cranial%20Sinuses); [Neuroanatomy, Superior Petrosal Sinus](https://www.ncbi.nlm.nih.gov/books/NBK547681/); [Neuroanatomy, Dural Venous Sinuses](https://www.ncbi.nlm.nih.gov/books/NBK482257/); Anatomy of the Human Body (20th ed.): Development of the Vascular System (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain. ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/superior-petrosal-sinus/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/superior-petrosal-sinus/