Final answer:
The cochlear nerve, a branch of the vestibulocochlear nerve, is formed by the axons of bipolar sensory neurons from the spiral organ and is responsible for relaying auditory information to the brain.
Step-by-step explanation:
The axons of bipolar sensory neurons from the spiral organ primarily form the cochlear nerve, which is a branch of the vestibulocochlear nerve (cranial nerve VIII). The bipolar neurons from the spiral ganglion carry auditory information that is processed by the cochlea. This information travels along the cochlear nerve, reaching the cochlear nucleus in the medulla, which is part of the brainstem. The cochlear nerve is specialized in transducing sound waves into neural signals which then travel to the brain for processing, giving us the ability to hear.
Understanding the inner ear's anatomy reveals the bony labyrinth, which includes both the cochlea for hearing and the vestibule for balance. These distinct sensory systems are carried side-by-side as the vestibulocochlear nerve. The cochlear branch, particularly, is responsible for conveying hearing information to the brain.