Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

Sense Organs. Analyzers
Organs of Hearing and Equilibrium (Vestibulocochlear Organ)
Organ of Hearing — Auditory Pathway of the Analyzer

The auditory Nerve Impulse is transmitted from the receptor Cells to the next Neurons located in the spiral ganglion of the cochlea, whose axons form the cochlear nerve. Subsequently, impulses travel along the fibers of the cochlear nerve to the Brain, reaching the dorsal and ventral cochlear nuclei situated in the Pons. The axons of these nuclear cells project to the subcortical auditory centers, where sound impulses are processed subconsciously. The subcortical auditory centers include the inferior colliculi of the Midbrain and the medial geniculate bodies of the metathalamus within the Diencephalon. Conscious sound perception, along with higher-level analysis and synthesis, takes place in the cortical center of the Auditory Analyzer, located in the cortex of the superior temporal gyrus, specifically within projection areas 41 and 42.

The auditory cortex is responsible for information Processing, including the analysis of sound signals and sound differentiation. It forms complex representations of auditory stimuli received separately from both ears and is also responsible for the spatial localization of sound.

Neural impulses traveling along the Auditory pathway to the inferior colliculi are relayed to one of the extrapyramidal tracts—the tectospinal tract. From there, the impulses are transmitted to the motor nuclei of the ventral horns of the Spinal Cord, and subsequently to the skeletal Muscles via these pathways.

Via the tectospinal tract, a complex reflex arc is completed, through which neural impulses trigger Skeletal Muscle contractions in response to specific sound signals (such as startle and defensive Reflexes).