thyroarytenoideus

The thyroarytenoideus, or thyroarytenoid muscle, is an intrinsic muscle of the larynx that forms a major part of the vocal fold body. It originates from the inner surface of the thyroid cartilage near the angle and inserts on the arytenoid cartilage, with fibers intermingling with the vocal ligament.

The muscle is traditionally described as having two functional parts: the thyrovocalis (vocalis) and the thyromuscularis. The thyrovocalis lies anteriorly and attaches to the vocal process of the arytenoid, while the thyromuscularis arises from the thyroid region and inserts at the muscular process of the arytenoid. Together these portions contribute to the bulk of the vocal folds and participate in voice production.

Functionally, the thyroarytenoid shortens and relaxes the vocal folds when contracted, lowering pitch. It works in concert with the cricothyroid muscle, which increases tension to raise pitch. The thyroarytenoid also plays a role in adduction and thickening of the vocal folds during phonation, influencing voice quality and loudness.

Innervation is provided by the inferior laryngeal nerve, a branch of the recurrent laryngeal nerve, while arterial supply comes from branches of the superior and inferior laryngeal arteries. Clinically, the muscle is central to normal phonation and can be involved in voice disorders arising from intrinsic laryngeal muscle dysfunction, aging, or nerve injury.