Anatomy

Origin

It arises from the broad depression on the corresponding half of the posterior surface of the lamina of the cricoid cartilage.

Insertion

Its fibers run upward and lateral ward, and converge to be inserted into the back of the muscular process of the arytenoid cartilage.    

Nerve

Recurrent Laryngeal Nerve (Branch of the Vagus nerve, CN X).

Actions

The Cricoarytenoidei posteriores separate the vocal folds, and, consequently, open the glottis, by rotating the arytenoid cartilages outward around a vertical axis passing through the cricoarytenoid joints; so that their vocal processes and the vocal folds attached to them become widely separated.