The auditory pathway is the central nervous system component of the auditory system. The auditory system belongs to the sensory systems and is responsible for auditory perception, or hearing. All information contained in sound is processed and evaluated by the auditory system. The auditory pathway consists of ascending and descending nerve tracts and the nuclei interposed within them[^1].
Anatomy
1. Neuron
The first neuron is located in the spiral ganglion of the cochlea. It is a bipolar nerve cell whose central processes travel with the cochlear nerve and terminate in the Cochlear nuclei in the Medulla oblongata.
2. Neuron
After entering the Brainstem, the cochlear nerve divides into two fiber tracts, which synapse onto the second neuron in the cochlear nuclei. After synapsing onto the second neuron, a distinction is made between a direct and an indirect part of the auditory pathway.
Direct part of the auditory pathway: This part runs from the Nucleus cochlearis posteriorLemniscus lateralisColliculus inferior
Indirect part of the auditory pathway: This part of the auditory pathway extends from the Ventral cochlear nucleus as the trapezoid body to the contralateral side. The superior olivary nuclei and the nuclei of the trapezoid body are interposed in the trapezoid body, where a large proportion of the fibers synapse onto the third neuron.
From each of the two cochlear nuclei, only a few fibers travel proximally on the ipsilateral side.
3. Neuron
From the nuclei mentioned above, the fibers ascend as the lateral lemniscus to the inferior colliculus, where many fibers synapse onto the fourth neuron and some fibers cross again.
4. Neuron
From the inferior colliculus, the fibers travel via the brachium of the inferior colliculus to the Corpus geniculatum medialeCapsula interna
5. Neuron
The fifth neuron terminates in the primary auditory cortex.
Primary auditory cortex
The primary auditory cortex is located in the Transverse temporal gyri of the of the temporal lobe
Secondary auditory cortex
The secondary auditory cortex is located lateral to the primary auditory cortex.