Definition of cocaine. : a bitter crystalline alkaloid C17H21NO4 obtained from coca leaves that is used especially in the form of its hydrochloride medically as a topical anesthetic and illicitly for its euphoric effects and that may result in a compulsive psychological need.
The inner hair cells transform the sound vibrations in the fluids of the cochlea into electrical signals that are then relayed via the auditory nerve to the auditory brainstem and to the auditory cortex.
This nerve also receives afferent sensory signals from the pharynx, tonsils, middle ear, and posterior of the tongue. Sensory fibers are also received from the carotid bodies, which detect increase in blood pressure in the sinus of the carotid.