Summary The Vestibulocochlear Nerve (CN VIII)

The Vestibulocochlear Nerve (CN VIII)


 The vestibulocochlear nerve is formed from 2 sets of fibres: vestibular and
cochlear
 This cranial nerve only has a sensory function

Anatomical course:
 Both sets of fibres arise from different nuclei in the brain:
1. Vestibular – from the vestibular nuclei in the pons and medulla
2. Cochlear – from the ventral and dorsal cochlear nuclei in the inferior
cerebellar peduncle
 Both fibres join in the pons to form the vestibulocochlear nerve
 The nerve exits the pons at the cerebellopontine angle and exits the cranium
through the internal acoustic meatus
 After exiting the cranium, the nerve splits into the vestibular and cochlear
nerves
 The vestibular nerve acts to innervate the vestibular system in the inner ear,
while the cochlear nerve travels to the cochlea, forming the spiral ganglia




Special sensory function:
 Hearing – the cochlea acts to detect the magnitude and frequency of sound
waves entering the ear
 The hair cells of the organ of Corti respond to vibrations of the basilar
membrane
 Action potentials travel from the spiral ganglia, which contain cell bodies from
the cochlear nerve
 The magnitude of the sound determines how much the basilar membrane
vibrates and therefore the frequency of action potentials