Subarcuate fossa

In adults, the petrous part of the temporal bone features a subtle depression known as the subarcuate fossa on its posterior surface, located superiorly and laterally in relation to the internal acoustic opening. This depression marks the origin of the subarcuate canaliculus—alternatively termed the petromastoid canal or the antrocerebellar canal of Chatellier—which establishes a pathway between the posterior cranial fossa and the mastoid cells adjacent to the antrum.

For newborns and young children, the fossa is a more prominent cavity that narrows into the subarcuate canaliculus, forming a conduit that links the mastoid cells to the posterior cranial fossa.

Both structures, the subarcuate fossa and the canaliculus, accommodate the protective dura mater and subarcuate vessels, crucial for providing blood to the nearby tissues and mastoid air cells. Typically, the subarcuate artery arises from either the anterior inferior cerebellar artery or the labyrinthine artery, while the vein associated with it may empty into the superior petrosal sinus or directly into the sigmoid sinus. There is evidence to suggest that the subarcuate canaliculus could serve as a passage for infections moving from the middle ear into the posterior cranial fossa, potentially leading to cerebellar abscesses. Such infections are often seen spreading from the tympanic cavity or mastoid cells, particularly in infants' first year.