It occupies the upper and back part of the larynx, a great portion of which it covers. It is the largest and most powerful of the intrinsic muscles connected with this organ.

Origin. - From the posterior broad surface of the cricoid cartilage.

Insertion. - Into the outer angle of the arytenoid cartilage.

Action. - To draw the arytenoid cartilages apart and dilate the opening into the larynx.