English: Vocal folds. When the intrinsic muscles of the larynx contract, they pull on the arytenoid cartilages, which causes them to pivot. Contraction of the posterior cricoarytenoid muscle, for example, moves the vocal folds apart (abduction), thereby opening the rima glottidis. By contrast, contraction of the lateralcricoarytenoid muscle moves the vocal folds together (adduction), therby closing the rima glottidis.