Stock Photo - VOCAL CORD, DRAWING The vocal cords. The vocal cords in blue correspond to folds of the larynx mucous membrane. They are tense between the arytenoid cartilage at the top and the thyroid cartilage at the bottom. The vocal cords are supported by a pair of folds, the vestibular folds. The vocal cords are in open position during respiration, and closed during phonation, vibrate during the air passing and then enabling the emission of sounds. The passage between these two states is made thanks to various muscles : the lateral and posterior crico_arytenoid muscles on the sides of the cricoid cartilage and above the cricoid cartilage, the arytenoid muscle beneath the cricoid cartilage. The contraction of the posterior cricoarytenoid muscles move the thyroid cartilage, separating the vocal cords. Contrarily, the contraction of the lateral cricoarytenoid muscles or the arytenoid muscle brings the vocal cords closer. The vocal muscles or thyro_arytenoideus muscles, running along the vocal cords, insure their tension.