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The auditory nerve (8th cranial nerve) is made up of two segments, the vestibular nerve segment and the cochlear nerve segment. The vestibular nerve is associated with sending information about equilibrium from the inner ear to the brain. The cochlear nerve is associated with the transmission of information about sound. The vestibular nerve splits into two branches, the inferior (lower) and superior (higher) vestibular nerves. These two nerve components lie next to each other and next to the cochlear nerve as they pass through the internal auditory canal, a small bony canal that leads from the inner ear to the brainstem. They also lie next to the 7th cranial nerve which is the facial nerve. The facial nerve activates the muscles for facial movement. The vestibular portion of the 8th cranial nerve is the site of origin in up to 95% of the cases of acoustic neuromas. Acoustic neuromas arise with equal frequency on the superior and inferior portion of the vestibular nerve.