Internal acoustic meatus

Last edited and medically reviewed by Alaric Steinmetz on 01.12.2023

Synonyms

IAM, Internal Acoustic Meatus

ICD-11

XA6ZY7

The internal acoustic meatus runs within the Temporal bone and is part of the inner ear.

Anatomy

Overall, the internal acoustic meatus extends approximately 1 cm within the temporal bone. The internal acoustic meatus opens via the internal acoustic porus into the posterior cranial fossa. The following anatomically relevant structures pass through the internal acoustic meatus:

Facial nerve
Nervus intermedius
Vestibulocochlear nerve
Arteria labyrinthi

Figure

Schematic illustration of the anatomical structures in the internal auditory canal, showing the crista transversa. Figure adapted from A. Rhoton.

Retrosigmoid craniotomy — Depiction of the vestibulocochlear nerve (CN VIII) and the internal acoustic meatus during a retrosigmoid approach. The facial nerve is obscured by the vestibulocochlear nerve and is not visible.

Imaging

Internal auditory canal on CT — Visualization of the internal auditory canal (red arrow) on an axial CT image.

Coronal MRI of the internal acoustic meatus — Depiction of the internal acoustic meatus (orange arrow) on a coronal T2-weighted MRI image of the neurocranium.