Internal acoustic meatus

Between the posterior cranial fossa and the inner ear of the petrous part of the temporal bone, the internal auditory meatus or internal acoustic meatus (meatus acusticus internus), opens on the internal auditory canal, or internal acoustic canal.

It is shallow and ended by a bottom (Fundus meatus acusticus internus) divided into four holes by two crests: a more or less horizontal one and a vertical one.

-The rostrodorsal hole, which is the broader, is the endocranial orifice of the facial canal (Canalis facialis):

for the facial nerve (CN VII) and:

-The dorsocaudal orifice is the superior vestibular opening.

-The ventrocaudal orifice is the inferior vestibular opening.

-The rostroventral orifice is the cochlear opening that presents a cribriform aspect

for the corresponding branches of the vestibulocochlear nerve (CN VIII).