vocal folds

The vocal folds, also known popularly as vocal cords, are composed of twin infoldings of mucous membrane stretched horizontally across the larynx. They vibrate, modulating the flow of air being expelled from the lungs during phonation. Open during inhalation, closed when holding one's breath, and vibrating for speech or singing (opening and closing 440 times per second when singing A above middle C); the folds are controlled via the vagus nerve. They are white because of scant blood circulation.
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