Internal auditory meatus

Internal auditory meatus
Left temporal bone. Inner surface.
Diagrammatic view of the fundus of the right internal acoustic meatus.
Details
Latin	meatus acusticus internus
Identifiers
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terms of bone [[[d:|edit on Wikidata]]]

The internal auditory meatus (also meatus acusticus internus, internal acoustic meatus, internal auditory canal, internal acoustic canal, or IAC) is a canal within the petrous part of the temporal bone of the skull between the posterior cranial fossa and the inner ear.

Function

The internal auditory meatus provides a passage through which the vestibulocochlear nerve, the facial nerve, and the labyrinthine artery (an internal auditory branch of the basilar artery) can pass from inside the skull to structures of the inner ear and face.

It also contains the vestibular ganglion.

Structure

The opening to the meatus is called the porus acusticus internus, or its English translation, the internal acoustic opening. It is located inside the posterior cranial fossa of the skull, 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 internal auditory meatus 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 facial nerve travels through the facial canal, eventually exiting the skull at the stylomastoid foramen.

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.

Additional images

• 

  Internal acoustic meatus

• 

  Temporal bone at birth. Inner aspect.

• Gray193.png

  Base of the skull. Upper surface.

• 

  Horizontal section through left ear; upper half of section.

• Gray923.png

  The cochlea and vestibule, viewed from above.

• 

  Tympanic cavity. Facial canal. Internal carotid artery.

References

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

See also

• External auditory meatus

External links

• Anatomy figure: 30:01-08 at Human Anatomy Online, SUNY Downstate Medical Center
• cranialnerves at The Anatomy Lesson by Wesley Norman (Georgetown University) (VII)
• Diagram of Porus acusticus internus
• Diagram of Porus acusticus internus