Within the auditory nerve are two types of fibre, vestibular and cochlear hence its alternative name. The nerve is formed in the internal meatus and then passes medially to join the brain stem at the cerebromedullary angle. Cochlear fibres arising from the bipolar spiral ganglion cells of the cochlea pass to the dorsal and ventral cochlear nuclei in the upper medulla. Efferent fibres cross to the opposite side to form the auditory striae in the floor of the fourth ventricle. Those from the ventral nucleus particularly forming the trapezoid body in the pons. Fibres ascend from the trapezoid body in the lateral lemniscus to reach the medial geniculate body and thence to the auditory cortex. Vestibular fibres arising from the semicircular ducts, saccule and utricle pass to the vestinbular ganglion in the internal meatus and ultimately terminate in the vestibular nuclei in the floor of the fourth ventricle. Efferent fibres travel to the cerebellum in the inferior cerebellar peduncle and there are other vestibular connections to the nuclei of cranial nerves II, IV, VI and XI via the medial longitudinal bundle.
Was this article helpful?
This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.