The pair of elastic, fibered bands inside the human larynx. The cords are covered with a mucous membrane and pass horizontally backward from the thyroid cartilage (Adam's apple) to insert on the smaller, paired arytenoid cartilages at the back of the larynx. The vocal cords act as sphincters for air regulation and may be vibrated to produce sounds. Separation, approximation, and alteration of tension are produced by action of laryngeal muscles acting on the pivoting arytenoids. Innervation is through branches of the vagus nerve. Vibration of the cords produces fundamental sounds and overtones. These can be modified by the strength of the air current, the size and shape of the glottis (the opening between the cords), and tension in the cords.