The Vocal Folds (plicœ vocales; inferior or true vocal cords) are concerned in the production of sound, and enclose two strong bands, named the vocal ligaments (ligamenta vocales; inferior thyroarytenoid). Each ligament consists of a band of yellow elastic tissue, attached in front to the angle of the thyroid cartilage, and behind to the vocal process of the arytenoid. Its lower border is continuous with the thin lateral part of the conus elasticus. Its upper border forms the lower boundary of the ventricle of the larynx. Laterally, the Vocalis muscle lies parallel with it. It is covered medially by mucous membrane, which is extremely thin and closely adherent to its surface.