Transverse arytenoid muscle

The transverse arytenoid muscle (a.k.a. the interarytenoid muscle, or transversus arytenoideus) is a single, unpaired intrinsic muscle of the larynx that plays a crucial role in adducting the arytenoid cartilages and closing the posterior part of the rima glottidis during phonation and swallowing.

Origin and Insertion

The muscle consists of horizontal fibres that extend from the posterior surface and lateral border of one arytenoid cartilage to the corresponding areas of the opposite arytenoid cartilage, forming a muscular bridge between them.

Innervation

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

Action

Contraction of the transverse arytenoid muscle draws the arytenoid cartilages together, bringing their vocal processes and the posterior parts of the vocal folds toward the midline. This action closes the intercartilaginous (posterior) portion of the glottis, contributing to voice production and airway protection.

Paralysis of this muscle, often as part of recurrent laryngeal nerve injury, can lead to incomplete glottic closure, resulting in breathy or weak phonation.