Inner ear, nearer auditory nerve, has one straight row of 3500 inner hair cells {hair cell, cochlea} and has three S-curved rows with 3500 outer hair cells each (10,500 total). Outer-hair-cell cilia poke through tectorial membrane. Hairs have long part, medium part, and short part, linked by hairs from small tip to medium middle and from medium tip to large middle. Cochlea hair-cell receptors microscopic fibers and microscopic cross-fibers cause resonance between frequencies.
Oval-window movement makes pressure waves, down vestibular canal, which cause middle-canal vertical movement, which slides tectorial-membrane gel horizontally over upright cilia. If pushed one way, hair-cell-membrane potential increases from resting potential. If pushed other way, potential decreases. Inner hair cells send to 10 to 30 auditory neurons.
Outer hair cells can receive brain signals to extend cilia, to stiffen cochlear partition and dampen sound. This reduces signal-to-noise ratio, lowers required input intensity to sharpen tuning, or sends secondary signals to inner hair cells.
Consciousness>Consciousness>Sense>Hearing>Anatomy>Cochlea
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Date Modified: 2022.0224