Falciform crescent
The falciform crescent is a horizontal ridge that divides the internal acoustic meatus into superior and inferior portions.
Superior
The facial nerve and superior vestibular nerve (SVN) travel in the superior portion of the IAM with the facial nerve anterior to the SVN and separated from it in the lateral portion by Bill's bar, a vertical ridge of bone.
Inferior
The cochlear nerve and inferior vestibular nerve (IVN) run inferior to the falciform crescent with the cochlear nerve situated more anteriorly.
