Nerve · Head

Vestibulocochlear nerve

Nervus vestibulocochlearis

Hearing and balance travel out of the inner ear together, in one sheath, as two nerves that never mix. The cochlear part carries sound from the spiral organ inside the cochlea; the vestibular part carries head position and acceleration from the three semicircular canals and the two otolith organs, which is how the body knows which way is up without looking. Both sets of fibres gather in ganglia buried in the petrous temporal bone, then run laterally out of the internal acoustic meatus in company with the facial nerve — a narrow, crowded bony tunnel shared by four structures. Crossing the cerebellopontine angle, they enter the brainstem at the junction of pons and medulla. It is a purely sensory nerve: it moves nothing.