Anatomophysiology of the central auditory nervous system: basic concepts.

The purpose of this review is to provide an overview of the central auditory nervous system (CANS). Three main relay nuclei are located between the auditory nerve and the primary auditory cerebral cortex: 1- the cochlear nucleus, 2- the contralateral inferior colliculus and 3- the contralateral medial geniculate body. Some fibers of this main ascending pathway branch off to other nuclei such as the nuclei of the superior olivary complex and the nucleus of the lateral lemniscus. Fiber tracts connect the two sides of the ascending pathway at several levels, in such a manner that each ear projects heavier to the contralateral temporal cortex. As sensory information travels within the CANS, its processing occurs not only in a serial order but also in a parallel manner resulting a highly efficient and redundant system. Finally, this review put forth a model of central auditory processing that can serve as the basis for evaluating and addressing the needs of eventual revalidation.