External part of thyroarytenoid muscle

Pars externa musculi thyreoarytenoidei

  • Latin synonym: Musculus thyreoarytenoideus externus; Pars lateralis musculi thyreoarytaenoidei
  • Synonym: Lateral part of thyroarytenoid muscle

Definition

Muhammad A. Javaid

The external part of thyroarytenoid muscle refers to the broad flat part of the thyroarytenoid muscle which lies lateral to the fibro-elastic membrane of the larynx and the laryngeal ventricles and saccules.

Origin

It originates from the inner surface of the thyroid cartilage near the angle and adjacent cricothyroid ligament.

Insertion

The muscle fibres run posteriorly and slightly laterally to insert into the anterolateral surface of the arytenoid cartilage.

Innervation

Recurrently laryngeal nerve (which is a branch of the vagus nerve)

Action

The contraction of external part of thyroarytenoid muscle draws the arytenoid cartilage forward toward the thyroid cartilage, thereby relaxing and shortening the vocal folds and lowering the pitch of the voice. It also helps narrow the rima glottidis during phonation.

References

  • Gray, H. (2016) Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 41st edn. Edited by S. Standring. New York: Elsevier. Chapter 35: Larynx, pp. 597.

  • Hoerter JE, Fakoya AO, Chandran SK. Anatomy, Head and Neck: Laryngeal Muscles. [Updated 2024 Jul 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK545265/