Which muscle is NOT intrinsic to the larynx?

• A. Omohyoid
• B. Interarytenoid
• C. Posterior Cricoarytenoid
• D. Thyroarytenoid

Answer: (A)

The key idea is distinguishing intrinsic laryngeal muscles, which have attachments entirely within the larynx and directly move the vocal folds, from extrinsic muscles that connect the larynx to outside structures and move the larynx as a whole. Omohyoid is an extrinsic muscle in the infrahyoid group, running from the scapula to the hyoid bone and primarily depressing the hyoid during swallowing. It does not act on the vocal folds themselves, so it’s not an intrinsic laryngeal muscle. The other muscles listed are intrinsic: interarytenoids connect arytenoid cartilages and help close the glottis; the posterior cricoarytenoid originates on the cricoid and inserts on the arytenoid to abduct the vocal folds; the thyroarytenoid sits between the thyroid and arytenoid, forming part of the vocal fold and adjusting tension. Since these all act directly on laryngeal structures, they are intrinsic.