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Transverse arytenoid muscle

The transverse arytenoid muscle is a key intrinsic muscle of the larynx, responsible for important movements in phonation and airway protection. It is an unpaired muscle that connects the two arytenoid cartilages, playing a crucial role in adducting (closing) the vocal folds. This muscle is essential in speech production and preventing aspiration during swallowing. Understanding its detailed anatomy, nerve and blood supply, as well as its appearance on MRI and CT, is vital for clinicians and radiologists.

Anatomy and Description

  • The transverse arytenoid muscle is a flat, unpaired band of skeletal muscle.

  • It runs horizontally between the posterior surfaces of the left and right arytenoid cartilages within the larynx.

  • Located deep to the oblique arytenoid muscles and forms part of the interarytenoid group.

Origin

  • Arises from the posterior surface and lateral border of one arytenoid cartilage.

Insertion

  • Inserts into the corresponding areas on the opposite arytenoid cartilage (posterior surface and lateral border).

Function

  • Primary function: Adducts (closes) the vocal folds by drawing the arytenoid cartilages together.

  • Essential for:

    • Closing the rima glottidis during swallowing to prevent aspiration.

    • Producing voiced sounds (phonation) by bringing the vocal cords into contact.

Nerve Supply

  • Recurrent laryngeal nerve, a branch of the vagus nerve (cranial nerve X), supplies the transverse arytenoid muscle.

Artery Supply

  • Primarily supplied by the laryngeal branches of the superior thyroid artery (branch of the external carotid artery).

  • Additional supply from the inferior thyroid artery (branch of the thyrocervical trunk).

Vein Supply

  • Venous drainage is via the laryngeal veins, which drain into the superior thyroid vein and subsequently into the internal jugular vein.

MRI Appearance

  • T1-weighted images: Appears as a low to intermediate signal intensity structure, similar to other skeletal muscles.

  • T2-weighted images: Normal muscle demonstrates relatively low signal intensity, but increased signal may indicate edema or pathology.

  • STIR (Short Tau Inversion Recovery): Demonstrates high signal intensity in cases of muscle edema, inflammation, or pathology; normal muscle appears suppressed/low signal.

CT Appearance

  • On CT, the transverse arytenoid muscle is seen as a soft-tissue band between the arytenoid cartilages posterior to the vocal folds.

  • It is best visualized in axial sections as a thin, isodense structure compared to other intrinsic laryngeal muscles.

MRI images

Transverse arytenoid muscle mri axial image