![]() Important earlier work was done by Schuknecht. A good anatomical description of human auditory nerve fibers is provided by Spoendlin and Schrott (1985). It projects centrally to the brainstem, where its fibers synapse with the cell bodies of the cochlear nucleus. In humans, this aspect of the nerve is roughly one inch in length. These central axons exit the cochlea at its base, where it forms a nerve trunk. The terms "cochlear nerve fiber" and "spiral ganglion cell" are used, to some degree, interchangeably, although the former may be used to more specifically refer to the central axons of the cochlear nerve. This name reflects the fact that the cell bodies, considered as a unit,has a spiral (or perhaps more accurately, a helical) shape, reflecting the shape of the cochlea. The cell bodies of the cochlear nerve lie within the central aspect of the cochlea and are collectively known as the spiral ganglion. Auditory nerve fibres provide synaptic connections between the hair cells of the cochlea and the cochlear nucleus within the brainstem. The number of fibers varies significantly across species-for example, the domestic cat has some 50,000 fibers. In humans, the number of nerve fibers within the cochlear nerve averages around 30,000. Both the peripheral process and the the axon are myelinated. In this respect, auditory nerve fibers are somewhat unique bipolar cells in that action potentials pass through the soma. Unlike the typical dendrite, the peripheral process generates and conducts action potentials, which then "jump" across the cell body (or somata) and continue to propagate along the central axon. ![]() The peripheral process is sometimes referred to as a dendrite, although that term is somewhat inaccurate. In terms of their anatomy, auditory nerve fibers are bipolar, with the most distal portion being called the peripheral process and the central projection being called the axon these two projection are also known as the "peripheral axon" and the "central axon". and is responsible for transmitting sound information from the inner ear to the brain. The cochlear nerve arises from within the cochlea and extends to the brainstem, where its fibers make contact with the cochlear nucleus, the next stage of neural processing in the auditory system. The other portion of the 8th nerve is the vestibular nerve. It is a sensory nerve, i.e., one that conducts information about the environment (in this case, acoustic energy that impinges on the external ear) to the brain. ![]() The acoustic nerve (also known as the auditory nerve or cochlear nerve is part of the vestibulocochlear nerve, (or 8th cranial nerve) that is found in higher vertebrates. ![]()
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