Vestibulocochlear Nerve (CN VIII)
The vestibulocochlear nerve is the eighth cranial nerve responsible for hearing and balance. It consists of two distinct divisions: the cochlear nerve for audition and the vestibular nerve for equilibrium. Both travel through the internal acoustic meatus alongside the facial nerve.
Origin
Cochlear: spiral ganglion in cochlea; Vestibular: vestibular ganglion (Scarpa's ganglion)
Foramina
Internal acoustic meatus
Course
Cochlea/vestibular apparatus → internal acoustic meatus → pontomedullary junction → cochlear and vestibular nuclei
Functions
- •Hearing (cochlear division)
- •Balance and spatial orientation (vestibular division)
- •Vestibulo-ocular reflex coordination
Branches
Structures Innervated
- →Hair cells of cochlea (hearing)
- →Hair cells of semicircular canals (rotational movement)
- →Hair cells of utricle and saccule (linear acceleration, gravity)
Clinical Testing
Hearing: whispered voice, finger rub, Weber and Rinne tests. Vestibular: Romberg test, Dix-Hallpike maneuver, head impulse test, nystagmus examination.
Clinical Relevance
Acoustic neuroma (vestibular schwannoma) typically presents with unilateral hearing loss, tinnitus, and imbalance. May compress adjacent facial nerve in cerebellopontine angle. Meniere's disease causes episodic vertigo, hearing loss, and tinnitus.
Study Tips
- ✓Weber lateralizes to affected ear in conductive loss, away in sensorineural
- ✓Rinne: Air > Bone = normal or sensorineural; Bone > Air = conductive loss
- ✓Acoustic neuroma: CPA tumor, CN VII and VIII symptoms, MRI for diagnosis
- ✓Vestibular vs cerebellar: vestibular nystagmus suppressed by fixation
Master Cranial Nerves with AI
Interactive AI tutor for neuroanatomy and clinical examination.
Download AnatomyIQVestibulocochlear Nerve (CN VIII) FAQs
Common questions about this cranial nerve
In Weber test, sound lateralizes to the affected ear in conductive loss (less ambient noise masking) and away in sensorineural loss (nerve doesn't work). Rinne compares air vs bone conduction: normally air>bone; reversed in conductive loss.
A benign tumor of Schwann cells on the vestibular nerve, typically at the cerebellopontine angle. Despite originating from vestibular nerve, hearing loss is usually the first symptom. Growth can compress facial nerve causing weakness.
Peripheral vertigo (inner ear, CN VIII) is typically more severe, with horizontal/torsional nystagmus suppressed by visual fixation. Central vertigo (brainstem, cerebellum) has vertical nystagmus, direction-changing nystagmus, and is not suppressed by fixation.