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Portrait of Larynx

Anatomy · Organs & viscera

Larynx

The voice box, at about C3 to C6

Neck · respiratory system

The larynx, or voice box, is the short cartilaginous tube at the top of the trachea, in the front of the neck at about the level of C3 to C6. It guards the airway during swallowing, houses the vocal folds and produces the pitch of the voice. Its framework is a set of nine cartilages: the single thyroid, cricoid and epiglottis, and the paired arytenoid, corniculate and cuneiform cartilages.

How to spot them

  • ▸A cartilaginous box below the hyoid bone and above the trachea, with the thyroid cartilage forming the 'Adam's apple'
  • ▸The cricoid cartilage below it is the only complete ring in the airway, shaped like a signet ring
  • ▸Inside, two vocal folds stretch from the thyroid cartilage in front to the arytenoids behind, with the slit between them being the rima glottidis
  • ▸Topped by the leaf-shaped epiglottis, which folds back over the entrance during swallowing

What to know

The largest of its cartilages, whose two plates meet at an angle of about 90 degrees in men and 120 in women, forming a prominence in the neck

Larynx — the thyroid cartilage forms the laryngeal prominence, the 'Adam's apple'.

The only complete ring of cartilage in the airway, shaped like a signet ring with its broad part at the back

The cricoid cartilage of the larynx.

The membrane between two of its cartilages that surgeons and paramedics can cut through in a life-threatening obstruction

The cricothyroid membrane, for emergency cricothyroidotomy.

The only muscle that opens the vocal folds, sometimes called the safety muscle of the voice box

The posterior cricoarytenoid muscle of the larynx.

Its left recurrent nerve loops under the aortic arch, so a chest tumour can leave the voice hoarse

The recurrent laryngeal nerve of the larynx.

A leaf-shaped cartilage that flaps down over the entrance to it during swallowing

The epiglottis, guarding the larynx.

The paired folds, covered in stratified squamous epithelium, whose opening is the glottis

The vocal folds of the larynx and the rima glottidis.

Key ideas

  • Pitch is controlled by the length and tension of the vocal folds; men's folds are longer and thicker after puberty, giving a lower voice.
  • The larynx sits lower in humans than in other primates, enlarging the pharynx as a resonating chamber, which helped speech evolve but makes choking easier.

Quick-fire facts

  • •Its nine cartilages are three single (thyroid, cricoid, epiglottis) and three pairs (arytenoid, corniculate, cuneiform).
  • •The thyroid cartilage is the largest and forms the Adam's apple, more prominent in men.
  • •The cricoid is at about C6 and marks the join with the trachea and the pharynx with the oesophagus.
  • •All the intrinsic muscles except cricothyroid are supplied by the recurrent laryngeal nerve; cricothyroid is supplied by the external branch of the superior laryngeal nerve.
  • •The hyoid bone lies above it, joined by the thyrohyoid membrane.
  • •The vestibular folds ('false cords') lie above the true vocal folds.
  • •The larynx is about 4 to 5 cm long in adults and is generally higher and smaller in women and children.
  • •Removal of the larynx (laryngectomy) leaves a permanent stoma in the neck; the first was performed by Theodor Billroth in 1873.

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Sources