Vestibulocochlear Nerve:
Schema Anatomy
1. Geniculum of facial nerve (site of
geniculate ganglion)
2. Greater petrosal nerve
3. Cochlear (spiral) ganglion
4. Vestibulocochlear nerve (CN VIII)
5. Chorda tympani nerve
6. Facial canal and nerve
7. Vestibular ganglion
Comment: The facial and vestibulocochlear nerves traverse
the internal acoustic meatus together. The facial nerve makes a sharp bend at
the level of the geniculate (sensory) ganglion of the facial nerve before
descending and exiting the skull through the stylomastoid foramen. It sends
preganglionic parasympathetic fibers to the pterygopalatine ganglion (via the
greater petrosal nerve) and to the submandibular ganglion (via the chorda
tympani nerve).
The vestibulocochlear nerve carries
special sensory fibers from the cochlea via the cochlear nerve (auditory) and
from the vestibular apparatus via the vestibular nerve (balance). These 2
branches join and leave the inner ear via the internal acoustic meatus to pass
to the brain.
Clinical: Vertigo is a symptom involving the peripheral
vestibular system or its central nervous system connections and is
characterized by the illusion or perception of motion. Hearing loss can be sensorineural,
suggesting a disorder of the inner ear or cochlear division of CN VIII.
Conductive hearing loss suggests a disorder of the external or middle ear
(tympanic membrane and/or middle ear ossicles).
