VAN 121: Veterinary Gross Anatomy-II (2+2)

Acoustic or auditory nerve

ACOUSTIC /AUDITORY/VESTIBULO- COHLEAR NERVE

• This is the nerve of sense of hearing and equilibrium.
• It arises from the medulla at the lateral part of the corpus trapezoideum just behind the preceding nerve.
• It has two roots vestibular and cochlear.
• The nerve passes outward along with the facial to the internal auditory meatus. Here it divides into two branches an upper vestibular and the lower cochlear nerves.
• In the internal auditory meatus this nerve presents the vestibular ganglion.
• The peripheral processes of the cells of the ganglion are then distributed to the maculae of the utricle and the saccule, and the cristae ampullaris of the semicircular canals of the internal ear.
• The cochlear nerve detaches a filament to the saccule and passes through the modiolus and joins the spiral ganglion.
• The peripheral processes of the cells of the ganglion run in the lamina spiralis and are distributed to the organ of corti in the cochlea.