Lateral cricoarytenoid muscle

The lateral cricoarytenoid (also anterior cricoarytenoid) is an intrinsic muscle of the larynx. It attaches at the cricoid cartilage anteriorly, and at the arytenoid cartilage of the same side posteriorly. It is innervated by the recurrent laryngeal nerve. It acts to close the rima glottidis, thus closing the airway.

Anatomy
The muscle is directed obliquely superoposteriorly from its anterior attachment to its posterior attachment.

Attachments
The muscle's anterior attachment is onto the superior border of the arch of the cricoid cartilage.

Its posterior attachment is onto the anterior aspect of the muscular process of the ipsilateral arytenoid cartilage.

Innervation
The muscle receives motor innervation from (branches of the anterior terminal division of) the recurrent laryngeal nerve (which is in turn a branch of a vagus nerve (CN X)).

Actions/movements
The muscle rotates the arytenoid cartilage medially (it thus acts as antagonist to the posterior cricoarytenoid muscle which rotates the cartilage laterally).

Function
The muscle closes the rima glottidis, adducting (approximating) the apices of the vocal process to close the ligamentous part of rima glottidis (in which it is synergystic with the oblique arytenoid muscles and transverse arytenoid muscle). It thus functions to close the airway.

It also shortens and slackens the vocal cords.