Anatomy of the vestibulocochlear nerve

1. Big picture

The vestibulocochlear nerve, cranial nerve VIII, is a pure special sensory nerve. It has two functionally different parts:

1. Cochlear nerve → hearing

2. Vestibular nerve → balance, head position, eye–head coordination

For the exam, the important logic is:

CN VIII enters the brainstem at the cerebellopontine angle → cochlear fibers go to the auditory pathway → vestibular fibers go to vestibular nuclei → vestibular nuclei connect with eye movement nuclei, cerebellum, spinal cord, reticular/autonomic centers.

That is why CN VIII lesions can cause:

• hearing loss,

• tinnitus,

• vertigo,

• nystagmus,

• nausea/vomiting,

• imbalance,

• deviation/falling toward one side.