What is the primary muscle responsible for abducting the vocal cords?

The primary muscle responsible for abducting the vocal cords is the posterior cricoarytenoid muscle. This muscle plays a critical role in the functioning of the larynx by pulling the arytenoid cartilages apart, which in turn separates the vocal cords and opens the glottis. This action is essential for breathing, particularly during inhalation, as it allows air to flow freely into the trachea.

In contrast, other muscles listed, such as the cricothyroid muscle and the thyroarytenoid muscle, primarily serve different functions. The cricothyroid muscle mainly adjusts the tension of the vocal cords to modulate pitch, while the thyroarytenoid muscle helps in shortening the vocal cords to lower pitch. The lateral cricoarytenoid muscle, on the other hand, is responsible for adducting the vocal cords, which is the opposite action of abduction.

Understanding the function of the posterior cricoarytenoid muscle is crucial for grasping how the laryngeal muscles work in concert to control the position and tension of the vocal cords, thus regulating airflow and sound production during phonation and respiration.