Internal auditory meatus

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Internal auditory meatus
Left temporal bone. Inner surface.
Diagrammatic view of the fundus of the right internal acoustic meatus.
Latin meatus acusticus internus
Gray's p.143
TA A02.1.06.033
FMA 53163
Anatomical terms of bone

The internal auditory meatus (also meatus acusticus internus, internal acoustic meatus, internal auditory canal, internal acoustic canal, or IAC) is a canal in the petrous part of the temporal bone of the skull, on each side, and serves as the passageway for the cranial nerves, namely cranial nerve VII and cranial nerve VIII, and for the labyrinthine artery, between the middle and inner ear.


The opening to the internal acoustic meatus is located inside the cranial cavity, near the center of the posterior surface of the petrous part of the temporal bone. The size varies considerably; its margins are smooth and rounded. The canal is short (about 1 cm) and runs laterally into the bone. At its end are the openings for three different canals, one of which is the facial canal.

The internal acoustic meatus transmits the facial and vestibulocochlear nerves and the labyrinthine artery (an internal auditory branch of the basilar artery). The facial nerve travels through the facial canal, eventually exiting the skull at the stylomastoid foramen.

The opening of the meatus is called the porus acusticus internus, or its English translation, the internal acoustic opening.

The antero-superior part transmits the facial nerve and nervus intermedius and is separated from the postero-superior section, which transmits the superior vestibular nerve, by Bill's bar (named by William F. House). The falciform crest or transverse crest separates the superior part from the inferior part. The cochlear nerve runs antero-inferiorly and the inferior vestibular nerve runs postero-inferiorly.

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This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

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