What action on the vocal cords is caused by the thyroarytenoid muscle?

The thyroarytenoid muscle plays a key role in voice production and the modulation of tension on the vocal cords. When this muscle contracts, it pulls the thyroid and arytenoid cartilages closer together, which effectively relaxes the vocal cords. This relaxation allows for a decrease in pitch and contributes to the lowering of vocal cord tension, enabling the production of lower frequency sounds.

In terms of the muscle's specific action, the thyroarytenoid does not elongate, adduct, or abduct the vocal cords; rather, its primary role is to help relax them. This action is crucial for fine-tuning vocal quality and is vital in various aspects of vocal performance and phonation.