NSCI 0817 Lecture Notes - Lecture 1: Cochlear Nucleus, Inferior Colliculus, Bony Labyrinth
8 May 2016
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Document Summary
Sound waves enter through the external auditory canal, or the ear canal, and cause the cone-shaped tympanic membrane to vibrate. The tympanic membrane passes on information such as frequency and amplitude of the stimulus to the auditory ossicles. Sounds of a lower pitch or frequency produce slower vibrations while higher frequency sounds produce faster vibrations. Lower amplitude or volume produces a less dramatic vibration, while higher amplitude produces a more dramatic vibration. The displacement of the membrane in turn vibrates the eardrum. The eardrum relays the stimulus onto the auditory ossicles, the three bones of the middle ear: the malleus, the incus, and the stapes. The stapes bone strikes the bony labyrinth in a piston- like fashion. The labyrinth is filled with fluid called perilymph that surrounds the hair cells. When the fluid is displaced, it causes the basilar membrane and the overlying organ of corti to move.
