What is the function of the spiral ganglion?

• A. It contains neuronal cell bodies whose axons form the auditory nerve.
• B. It acts as a relay for vestibular signals.
• C. It produces endolymph.
• D. It transmits auditory information to the brain.

Answer: (A)

The spiral ganglion houses the cell bodies of the primary auditory neurons. These neurons have peripheral processes that contact the hair cells in the organ of Corti, converting mechanical vibrations into electrical signals. The cell bodies’ central processes bundle together to form the cochlear nerve, a branch of the vestibulocochlear nerve, which carries auditory information to the brainstem for further processing. This is why its main function is described as containing neuronal cell bodies whose axons form the auditory nerve. It does not relay vestibular signals (that’s the vestibular ganglion), nor does it produce endolymph (that’s the stria vascularis).