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Structure

Larynx

Not medically reviewed · Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The larynx is a cartilaginous organ at the entrance to the lower airway that protects the airway during swallowing and produces voice. It lies in the anterior neck between the pharynx and the trachea.

Terminologia Anatomica (Latin): Larynx · Open in the 3D atlas

Location

In the adult it extends roughly from C3 to C6, with its lower border at the cricoid cartilage continuing as the trachea. It is higher in children and in women. The laryngeal cavity is divided by the vocal folds into supraglottic, glottic and subglottic regions.

Structure

The skeleton comprises the unpaired thyroid, cricoid and epiglottic cartilages and the paired arytenoid, corniculate and cuneiform cartilages, joined by membranes, ligaments and the cricothyroid and cricoarytenoid joints. The intrinsic muscles move the vocal folds; the vocal folds and the rima glottidis lie at the glottic level.

Blood supply

The superior laryngeal artery (from the superior thyroid artery) supplies the region above the vocal folds, and the inferior laryngeal artery (from the inferior thyroid artery) supplies the region below. Veins accompany the arteries to the thyroid veins.

Innervation

The internal branch of the superior laryngeal nerve gives sensation above the vocal folds, and the recurrent laryngeal nerve gives sensation below them and motor supply to all intrinsic muscles except the cricothyroid. The cricothyroid is supplied by the external branch of the superior laryngeal nerve. All derive from the vagus nerve.

Function

The larynx closes the airway during swallowing, regulates airflow and allows coughing and the Valsalva manoeuvre. It generates voice by vibration of the adducted vocal folds, with pitch controlled by tension and length and with the resonators of the pharynx, mouth and nose shaping speech.

Clinical correlations

Injury to the recurrent laryngeal nerve (for example during thyroid or neck surgery, or by mediastinal disease on the left because of its longer course) causes hoarseness; the posterior cricoarytenoid is the only abductor of the vocal folds. Cricothyrotomy through the cricothyroid membrane is an emergency airway route, and laryngeal oedema or epiglottitis can obstruct the airway.

Common exam points

  • Extends about C3 to C6; continues as the trachea at the lower border of the cricoid cartilage.
  • Unpaired cartilages: thyroid, cricoid, epiglottic; paired: arytenoid, corniculate, cuneiform.
  • All intrinsic muscles are supplied by the recurrent laryngeal nerve except the cricothyroid (external laryngeal nerve).
  • Posterior cricoarytenoid is the only muscle that abducts the vocal folds.
  • Sensation: internal laryngeal nerve above the vocal folds, recurrent laryngeal nerve below.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Netter FH. Atlas of Human Anatomy. Elsevier — Tier 3 (textbook)

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