Which muscle is the only intrinsic laryngeal muscle that abducts the vocal cords?

• A. Lateral cricoarytenoid
• B. Interarytenoid
• C. Posterior cricoarytenoid
• D. Thyroarytenoid

Answer: (C)

Abduction of the vocal cords is achieved by the posterior cricoarytenoid muscle, the only intrinsic laryngeal muscle that opens the glottis. It originates from the posterior cricoid and inserts on the muscular process of the arytenoid; when it contracts, it rotates the arytenoid cartilage laterally, pulling the vocal folds away from the midline to widen the rima glottidis for airflow during breathing. Other intrinsic muscles either adduct the cords to close the glottis (lateral cricoarytenoid and interarytenoids) or adjust tension within the vocal folds (thyroarytenoid). The posterior cricoarytenoid is unique in producing abduction.