The canal which comprises the internal auditory meatus is short (about 1 cm) and runs laterally into the bone.

[1] The fundus is subdivided by two thin crests of bone to form three separate canals, through which course the facial and vestibulocochlear nerve branches.

[citation needed] The falciform crest first divides the meatus into superior and inferior sections; a vertical crest (Bill's bar, named by William F. House) then divides the upper passage into anterior and posterior sections.

[2] Although there are three osseous canals, the fundus is conceptually divided more commonly into four quadrant areas according to the four major nerve branches of the inner ear: The cochlear and vestibular branches of cranial nerve VIII separate according to this schema and terminate in the inner ear.

The internal auditory meatus provides a passage through which the vestibulocochlear nerve (CN VIII), the facial nerve (CN VII), and the labyrinthine artery (an internal auditory branch of the anterior inferior cerebellar artery in 85% of people) can pass from inside the skull to structures of the inner ear and face.