Topics

Topic

design image
Vocalis muscle

The Vocalis muscle is a key intrinsic muscle of the larynx, playing a vital role in controlling the tension of the vocal cords and fine-tuning the pitch and quality of the human voice. Situated within the true vocal fold, the Vocalis muscle is intimately related to the thyroarytenoid muscle and is essential for normal phonation and vocal cord vibration. A thorough understanding of its anatomy, function, neurovascular supply, and imaging features is critical for clinicians, otolaryngologists, and radiologists.

Anatomical Description

  • The Vocalis muscle is a medial, specialized part of the thyroarytenoid muscle.

  • It lies parallel and immediately lateral to the vocal ligament within the vocal fold.

  • Appears as a thin band of muscle on imaging and in anatomical dissection.

Function

  • Adjusts tension of the vocal ligament, allowing fine control of pitch and timbre during speech and singing.

  • Acts to shorten and relax the vocal cords, lowering pitch.

  • Modulates subtle movements required for precise phonation.

Origin

  • Arises from the inner surface of the angle of the thyroid cartilage (close to the midline, near the anterior commissure).

Insertion

  • Attaches to the vocal process and the anterolateral surface of the arytenoid cartilage.

  • Some fibers are interspersed with the vocal ligament itself.

Nerve Supply

  • Innervated by the recurrent laryngeal nerve, a branch of the vagus nerve (cranial nerve X).

Arterial Supply

  • Supplied by branches of the superior laryngeal artery (from the superior thyroid artery).

  • May also receive blood from the inferior laryngeal artery (from the inferior thyroid artery).

Venous Drainage

  • Venous blood drains primarily into the superior laryngeal vein and inferior laryngeal vein.

  • These veins ultimately drain into the superior and inferior thyroid veins.

MRI Appearance

  • T1-weighted images: Vocalis muscle appears as a thin, hypointense (dark) band lateral to the hypointense vocal ligament, within the true vocal fold.

  • 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 may be mildly hyperintense; useful in detecting edema or inflammation within the muscle.

CT Appearance

  • On CT scans, the Vocalis muscle is seen as a thin, soft-tissue density structure lateral to the vocal ligament, within the true vocal cord.

  • It is best visualized on thin-slice axial and coronal images.

MRI images

Vocalis muscle MRI AXIAL IMAGE