Lateral cricoarytenoid muscle

The lateral cricoarytenoid muscle is a paired intrinsic muscle of the larynx that serves as one of the primary adductors of the vocal folds.

Origin

The lateral cricoarytenoid muscle originates from the upper border of the arch of the cricoid cartilage.

Insertion

The muscle fibres extends posteriorly and superiorly to insert into the muscular process of the arytenoid cartilage.

Innervation

The muscle is innervated by the recurrent laryngeal nerve, a branch of the vagus nerve (cranial nerve X).

Action

When the lateral cricoarytenoid muscle contracts, it rotates the arytenoid cartilage medially, drawing the vocal processes toward the midline and thereby adducting the vocal folds to close the rima glottidis, particularly the anterior (intermembranous) part. This action is essential for phonation and airway protection during swallowing.

Dysfunction or paralysis of this recurrent laryngeal nerve results in incomplete closure of the glottis, leading to hoarseness and air leak during phonation.