Origin: Posterior part of the cricoid
Insertion: Muscular process of the arytenoid cartilage
Nerve: Recurrent laryngeal branch of the vagus
Action: Abducts and laterally rotates the cartilage, pulling the vocal ligaments away from the midline and forward and so opening the rima glottidis
Antagonist: Lateral cricoarytenoid muscle
The Cricoarytaenoideus posterior (posterior cricoarytenoid) arises from the broad depression on the corresponding half of the posterior surface of the lamina of the cricoid cartilage; its fibers run upward and lateralward, and converge to be inserted into the back of the muscular process of the arytenoid cartilage. The uppermost fibers are nearly horizontal, the middle oblique, and the lowest almost vertical.