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Petrous Ridge

margo superior partis petrosae ossis temporalis

The petrous ridge (superior petrosal ridge) is the sharp superior border of the petrous portion of the temporal bone, separating the middle cranial fossa (anterosuperior) from the posterior cranial fossa (posteroinferior). The superior petrosal sinus runs in a groove along the petrous ridge from the cavernous sinus to the sigmoid sinus at the petromastoid junction. The trigeminal nerve (CN V) crosses over the apex of the petrous ridge to enter Meckel cave.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The petrous ridge is the approach landmark for middle fossa (Kawase) approaches to the CPA and the internal auditory canal: the greater superficial petrosal nerve, the arcuate eminence, and the petrous ridge define the surgical anatomy in this approach. Acoustic neuromas extending medially can be reached through the posterior face of the petrous bone inferior to the ridge. The petrous ridge is also the dural attachment of the tentorium cerebelli, making it relevant in posterior fossa decompression for tentorial incisura pathology.

Pathology

Common Injuries & Conditions

Petrous Ridge Anatomy in Kawase Middle Fossa Approach

The middle fossa (Kawase) approach to the posterior fossa drills the posterior petrous apex medial to the arcuate eminence and the greater superficial petrosal nerve up to the petrous ridge, exposing the petrous apex and Meckel cave for trigeminal schwannoma and petroclival meningioma resection without posterior fossa craniotomy.