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Thyroarytenoid muscle

The thyroarytenoid muscle is a key intrinsic muscle of the larynx, playing a crucial role in voice production by regulating tension and mass of the vocal cords. It lies within the larynx, forming the bulk of the vocal fold and running parallel to the vocal ligament. Understanding its detailed anatomy, function, neurovascular supply, and imaging characteristics is vital for otolaryngologists, radiologists, and clinicians involved in laryngeal pathology.

Anatomy and Description

  • Location: Intrinsic muscle of the larynx, located within each vocal fold.

  • Shape: Short, broad, paired muscle.

  • Structure: Lies lateral to the vocal ligament and medial to the lateral cricoarytenoid muscle.

Origin and Insertion

  • Origin: Inner surface of the angle of the thyroid cartilage (below the attachment of the epiglottis).

  • Insertion: Anterolateral surface and vocal process of the arytenoid cartilage.

Function

  • Primary Function: Relaxes and shortens the vocal cords, lowering the pitch of the voice.

  • Additional Role: Contributes to sphincteric closure of the laryngeal inlet during swallowing.

  • Clinical Significance: Lesions or paralysis may result in hoarseness or dysphonia.

Nerve Supply

  • Motor Innervation: Recurrent laryngeal nerve (branch of the vagus nerve, cranial nerve X).

Artery Supply

  • Primary Arteries:

    • Inferior laryngeal branch of the inferior thyroid artery (main supply).

    • Superior laryngeal branch of the superior thyroid artery (supplementary supply).

Vein Supply

  • Venous Drainage:

    • Corresponding inferior laryngeal vein drains into the inferior thyroid vein.

    • Superior laryngeal vein drains into the superior thyroid vein.

Imaging Appearance

  • MRI Appearance

    • T1-weighted Images: Intermediate to low signal intensity, isointense to surrounding muscle.

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

    • STIR (Short Tau Inversion Recovery): Mildly hyperintense; increased signal may indicate edema, inflammation, or denervation changes.

  • CT Appearance

    • Appears as a soft tissue band within the true vocal fold, lateral to the vocal ligament.

MRI images

Thyroarytenoid muscle mri axial image