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Oblique arytenoid muscle

The oblique arytenoid muscle is a small yet crucial intrinsic muscle of the larynx, playing a significant role in vocal fold movement and airway protection during swallowing. This muscle forms an “X” shape as its fibers cross from one arytenoid cartilage to the other, contributing to the closure of the laryngeal inlet. Understanding its detailed anatomy, function, and imaging characteristics is essential for professionals dealing with laryngeal disorders and interpreting head and neck imaging.

Anatomy and Description

  • Type: Intrinsic laryngeal muscle

  • Shape: Narrow, paired, crossing muscle fibers forming an “X” pattern over the arytenoid cartilages

  • Location: Posterior aspect of the larynx, superficial to the transverse arytenoid muscle

Origin

  • Posterior surface and muscular process of one arytenoid cartilage

Insertion

  • Apex of the opposite arytenoid cartilage

  • Some fibers continue as the aryepiglottic muscle into the aryepiglottic fold

Function

  • Adducts the arytenoid cartilages, aiding in the closure of the rima glottidis (vocal fold closure)

  • Closes the laryngeal inlet during swallowing, preventing aspiration

Nerve Supply

  • Recurrent laryngeal nerve (branch of the vagus nerve, cranial nerve X)

  • Provides motor innervation

Artery Supply

  • Laryngeal branches of the superior thyroid artery (branch of the external carotid artery)

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

Vein Supply

  • Superior laryngeal vein and inferior laryngeal vein

  • These veins drain into the superior thyroid vein and then into the internal jugular vein

MRI Appearance

  • T1-Weighted Images: The oblique arytenoid muscle appears as a small, intermediate to low signal structure overlying the arytenoid cartilages, best visualized in axial or coronal planes.

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

  • STIR (Short Tau Inversion Recovery): The muscle is hypointense (dark) compared to surrounding fatty tissue, providing good contrast for detecting edema or inflammation.

CT Appearance

  • Appears as a soft tissue density muscle overlying the arytenoid cartilages

  • Best visualized on axial or coronal thin-slice images

MRI images

Oblique Arytenoid Muscle MRI AXIAL IMAGE