The internal acoustic meatus
(also internal auditory meatus
) is a canal in the temporal bone
of the skull that carries nerves from inside the cranium towards the middle and inner ear compartments.
The opening to the internal acoustic meatus is located inside the cranial cavity, near the center of the posterior surface 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
Unlike the external acoustic meatus, the internal acoustic meatus does not transmit sound waves. It instead 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.