Final answer:
The posterior cricoarytenoid muscle is crucial for opening the vocal folds, enabling breathing and voice production.
Step-by-step explanation:
The posterior cricoarytenoid muscle is involved in the control of vocal cords and breathing. It is the only muscle that opens the vocal folds, allowing air to pass through the larynx. When the posterior cricoarytenoid muscles contract, they pull the arytenoid cartilages in a way that causes the vocal folds to move apart, opening the airway for respiration. This action is essential for normal breathing and is also a crucial aspect of voice modulation. Dysfunction of this muscle can lead to voice disorders or breathing difficulties.
In summary, the posterior cricoarytenoid muscle plays a vital role in respiratory mechanics and voice production, by controlling the abduction of the vocal folds which facilitates breathing and vocalization.