Neuroanatomy, neurophysiology, and central auditory assessment. Part III: Corpus callosum and efferent pathways.

In this, the last of a three-part series on neuroanatomy/physiology related to central auditory assessment, two topics will be presented: the corpus callosum and the efferent auditory system. A general anatomical description of the corpus callosum is followed by information on the topographical representation of the cortex within the corpus callosum. Auditory areas of the corpus callosum and the transcallosal auditory pathway are emphasized. Data on transfer time across the corpus callosum and the possible role of inhibitory and excitatory fibers of this commissure are presented. Neuropsychological studies relative to neuroanatomy/physiology of the corpus callosum are discussed, and the efferent auditory system from cortex to cochlea is described. Emphasis is placed on the structure and function of the olivocochlear bundle along with some clinical relationships to probable disorders of the descending pathway of the caudal brain stem.