Petromastoid canal

Last revised by Frank Gaillard on 19 Jun 2024

The petromastoid canal (also known as the subarcuate canaliculus or antrocerebellar canal of Chatellier) is a channel in the petrous temporal bone that joins the mastoid antrum to the posterior cranial fossa. It contains the subarcuate artery and vein 1.

The majority of petromastoid canals are small (<0.5mm diameter in over 50% of cases 1) and sometimes not visualized.

Radiographic features

CT

The petromastoid canal can usually be identified on sufficiently high-quality thin bone-algorithm CT of the temporal bone, although in a minority of patients no canal will be seen. When identified it is seen as a thin canal passing above the horizontal semicircular canal, between the ascending and descending limb of the superior semicircular canal. It usually has a slight anterior convex course 2.

Differential diagnosis

It is important not to mistake the petromastoid canal for a base of skull fracture 2.

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