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Lateral cricoarytenoid muscle

The lateral cricoarytenoid muscle is an intrinsic muscle of the larynx, crucial for voice production and airway protection. It is paired and fan-shaped, originating from the cricoid cartilage and inserting onto the muscular process of the arytenoid cartilage. This muscle plays a key role in adducting the vocal cords, thereby closing the rima glottidis during phonation and swallowing.

Synonyms

  • LCA muscle

  • Musculus cricoarytenoideus lateralis (Latin)

  • Lateral crico-arytenoid muscle

Function

  • Primary adductor of the vocal folds

  • Closes the rima glottidis (glottic space) by rotating the arytenoid cartilages medially

  • Essential for phonation and prevention of aspiration during swallowing

Origin

  • Superior border and anterolateral surface of the arch of the cricoid cartilage

Insertion

  • Muscular process of the arytenoid cartilage (on the same side)

Nerve Supply

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

  • Provides motor innervation

Arterial Supply

  • Branches of the superior laryngeal artery (from the superior thyroid artery)

  • Branches of the inferior laryngeal artery (from the inferior thyroid artery)

Venous Drainage

  • Superior laryngeal vein (drains into the superior thyroid vein)

  • Inferior laryngeal vein (drains into the inferior thyroid vein)

MRI Appearance

  • T1-weighted:
    Isointense  to surrounding skeletal muscle

  • T2-weighted:Isointense  to surrounding skeletal muscle

  • STIR (Short Tau Inversion Recovery):
    Muscle is usually hypointense, with high signal seen only in cases of edema, inflammation, or injury

CT Appearance

  • Appears as a small, well-defined soft tissue density lateral to the cricoid and arytenoid cartilages

  • Differentiated from adjacent fat and air spaces by higher attenuation

  • Best visualized on axial and coronal images in thin sections

MRI images

Lateral cricoarytenoid muscle mri axial image