Cochlear aqueduct

Last revised by Francis Deng on 1 Jan 2021

The cochlear aqueduct or canaliculus is a small canal in the bony labyrinth of the petrous temporal bone that contains the perilymphatic duct, which drains perilymph into the cerebrospinal fluid of the posterior cranial fossa subarachnoid space. It runs inferior and parallel to the internal auditory canal.

The lateral end arises from the scala tympani at the basal turn of the cochlea. It then courses through the otic capsule and petrous apex. These parts are very small in caliber and not visualized on CT in most patients 4.

The medial end, which is funnel-shaped and visible on CT in the vast majority of patients, opens at the roof (pyramidal fossa) of the jugular foramen pars nervosa 4. Within the pars nervosa, it is seen superior to the petrosal fossula.

Related pathology

Enlarged cochlear aqueduct is a controversial entity with few reported cases with attributable inner ear dysfunction 4.

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