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.
Trochlear nerve (IV) The trochlear nerve is part of the cranial nerve group responsible for innervation of the muscles of the head. The trochlear nerve originates from the dorsal mid-brain and is a motor nerve. It is composed of general somatic efferent fibres and is the smallest of the cranial nerves.