vestibulococlear

The vestibulocochlear nerve, or cranial nerve VIII, is a sensory cranial nerve that transmits auditory and vestibular information from the inner ear to the brain. It comprises two functional components: the cochlear nerve, which carries hearing information, and the vestibular nerve, which carries information about balance and spatial orientation. The two components join to form the vestibulocochlear nerve within the internal acoustic meatus of the temporal bone.

Anatomy and connections: The nerve emerges from the brainstem at the pontomedullary junction and travels through the internal acoustic meatus, alongside the facial nerve. Sensory cell bodies reside in the spiral ganglion (cochlear) and the vestibular or Scarpa’s ganglion (vestibular). The cochlear nerve projects to the cochlear nuclei in the medulla, while the vestibular nerve projects to the vestibular nuclei in the brainstem. From these nuclei, auditory pathways proceed to the inferior colliculus, the medial geniculate body of the thalamus, and the auditory cortex; vestibular information contributes to gaze stabilization via the vestibulo-ocular reflex and to balance and spatial orientation via vestibulospinal and vestibulothalamic pathways.

Clinical relevance: Lesions of the vestibulocochlear nerve can cause sensorineural hearing loss, vertigo, tinnitus, and nystagmus. Vestibular schwannoma (acoustic neuroma) is a common tumor arising from Schwann cells of CN VIII and typically presents with unilateral hearing loss and balance disturbance. Diagnosis relies on audiometry and magnetic resonance imaging; management may include observation, surgical resection, or stereotactic radiosurgery.

Development and variation: The nerve is part of the peripheral nervous system; its sensory cell bodies reside in the spiral and Scarpa’s ganglia. Blood supply is mainly from the labyrinthine artery.