The Vestibulocochlear Nerve (CN VIII) - Podcast Version TeachMeAnatomy 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The vestibulocochlear nerve is the eighth paired cranial nerve. It is comprised of two parts – vestibular fibres and cochlear fibres. Both have a purely sensory function. In this article, we will look at the anatomy of the vestibulocochlear nerve – its anatomical course, special sensory functions and clinical relevance. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Anatomical Course The vestibular and cochlear portions of the vestibulocochlear nerve are functionally discrete, and so originate from different nuclei in the brain: Vestibular component – arises from the vestibular nuclei complex in the pons and medulla of the brainstem. Cochlear component – arises from the ventral and dorsal cochlear nuclei, situated within the medulla. Both sets of fibres combine in the pons to form the vestibulocochlear nerve. The nerve emerges from the brain at the cerebellopontine angle and exits the cranium via the internal acoustic meatus of the temporal bone. Within the distal aspect of the internal acoustic meatus, the vestibulocochlear nerve splits, forming the vestibular nerve and the cochlear nerve. The vestibular nerve innervates the vestibular system of the inner ear, which is responsible for detecting balance. The cochlear nerve travels to cochlea of the inner ear, forming the spiral ganglia which serve the sense of hearing. By TeachMeSeries Ltd (2025) Fig 1The origin of the vestibulocochlear nerve from the cerebellopontine angle Clinical Relevance Basilar Skull Fracture A basilar skull fracture is a fracture of the skull base, usually resulting from major trauma. The vestibulocochlear nerve can be damaged within the internal acoustic meatus, producing symptoms of vestibular and cochlear nerve damage. Patients may also exhibit signs related to the other cranial nerves, bleeding from the ears and nose, and cerebrospinal fluid leaking from the ears (CSF otorrhoea) and nose (CSF rhinorrhoea). Special Sensory Functions The vestibulocochlear nerve is unusual because it is formed mainly of bipolar neurones, which have two separate processes that transmit information for hearing and balance. Hearing Hearing is detected in the cochlea, where inner hair cells sense the magnitude and frequency of sound waves. These cells open ion channels when the basilar membrane vibrates, producing action potentials in neurones of the cochlear nerve, Magnitude – encoded by basilar membrane movement (larger vibrations generate action potentials more often) Frequency – encoded by the position of the activated inner hair cells along the membrane. This sensory information then travels centrally and is processed within the cochlear nuclei of the brainstem. Equilibrium (Balance) Balance is detected by the vestibular apparatus, which monitors changes in head position and movement. Hair cells in the otolith organs detect linear acceleration, while those in the semicircular canals detect rotation. The signals produced by these vestibular hair cells travel along the vestibular nerve to the brainstem. Their pattern encodes the direction and speed of head movement. This information is received and integrated within the vestibular nuclei, which coordinate balance and stabilise gaze through reflex pathways. By TeachMeSeries Ltd (2025) Fig 2The components of the membranous labyrinth. Clinical Relevance Vestibular Neuritis Vestibular neuritis refers to inflammation of the vestibular branch of the vestibulocochlear nerve. The aetiology of this condition is not fully understood, but some cases are thought to be due to reactivation of the herpes simplex virus. It presents with symptoms of vestibular nerve damage: Vertigo – a false sensation that oneself or the surroundings are spinning or moving. Nystagmus – a repetitive, involuntary to-and-fro oscillation of the eyes. Loss of equilibrium (especially in low light). Nausea and vomiting. The condition is usually self-resolving. Treatment is symptomatic, usually in the form of anti-emetics or vestibular suppressants Clinical Relevance Benign Paroxysmal Positional Vertigo (BPPV) BPPV is a common cause of brief, position-triggered episodes of vertigo. It occurs when small calcium crystals from the otolith organs migrate into one of the semicircular canals. Their presence disrupts the normal detection of rotational movement by stimulating vestibular hair cells inappropriately. These abnormal signals travel along the vestibular nerve and are interpreted within the vestibular nuclei as sudden rotation that does not match the actual movement of the head. This mismatch produces vertigo, imbalance, and characteristic positional nystagmus. The Dix–Hallpike test and Epley manoeuvre assess and treat the condition by guiding the displaced crystals back into the utricle. Do you think you’re ready? Take the quiz below Pro Feature - Quiz The Vestibulocochlear Nerve (CN VIII) Question 1 of 3 Submitting... Skip Next Rate question: You scored 0% Skipped: 0/3 1800 More Questions Available Upgrade to TeachMeAnatomy Pro Challenge yourself with over 1800 multiple-choice questions to reinforce learning Learn More Rate This Article