Larynx: cartilages, glottis and laryngeal nerves

Applied anatomy

The voice box is a frame of cartilages around the vocal folds, moved by two branches of the vagus nerve; nerve damage changes the voice or the airway.

Updated Nov 5, 2026

See it in 3D: Thyroid cartilage · Cricoid cartilage · Arytenoid cartilages · Epiglottis · Vocal folds · Recurrent laryngeal nerves · Superior laryngeal nerve

Key points

Large cartilages: thyroid (largest, the 'Adam's apple'), cricoid (lower ring) and epiglottis; small paired: arytenoids, corniculates, cuneiforms.
Recurrent laryngeal nerve: all intrinsic muscles except the cricothyroid, plus sensation below the vocal folds; the posterior cricoarytenoid is the only muscle that opens the folds.
The left recurrent nerve loops under the aortic arch, the right under the subclavian artery: left palsy can come from lung cancer or a big heart or vessels (Ortner syndrome).
Superior laryngeal nerve: internal branch gives sensation above the folds (cough reflex); external branch supplies the cricothyroid (pitch) and runs next to the superior thyroid artery.
Unilateral palsy: hoarse, breathy voice and choking on liquids; bilateral palsy: noisy breathing and airway danger, may need a tracheostomy.
The cricothyroid membrane, between the thyroid and cricoid cartilages, is the emergency surgical airway site.

What it is

The larynx sits at the top of the trachea and has three jobs: protect the airway during swallowing, let air through, and make voice. Its frame is the thyroid, cricoid and epiglottic cartilages with the small paired arytenoids that move the vocal folds. All the intrinsic muscles are supplied by the recurrent laryngeal nerve except the cricothyroid, supplied by the external branch of the superior laryngeal nerve. The long course of the recurrent nerve through the neck and chest explains why thyroid surgery, lung cancer and heart or great vessel disease can cause hoarseness.

Applied anatomy

Thyroid cartilage in front; cricoid cartilage below it, a complete ring; epiglottis above, closing over the inlet during swallowing.
Arytenoids sit on the cricoid and move the vocal folds; corniculate and cuneiform cartilages support the folds of the inlet.
Vestibular folds (false cords) above the true vocal folds; the glottis is the folds plus the space between them.
Subdivisions: supraglottis (above the folds), glottis, subglottis (below the folds down to the cricoid).
Cricothyroid membrane: between the lower edge of the thyroid and the cricoid cartilage.

Laryngeal nerve lesions and what you see

Nerve injured	Typical cause	What the patient has
One recurrent laryngeal nerve	Thyroid or neck surgery, lung or thyroid cancer, chest tumours, cardiovascular enlargement (left)	Hoarse or breathy voice, weak cough, choking on liquids
Both recurrent laryngeal nerves	Thyroid surgery, neurological disease	Folds stay near the midline: stridor and breathlessness; airway emergency
External branch of the superior laryngeal nerve	Thyroid surgery (near the superior thyroid artery)	Voice tires, cannot reach high notes
Internal branch of the superior laryngeal nerve	Surgery or trauma at the thyrohyoid membrane	Loss of sensation above the folds, weak cough reflex, aspiration

Clinical correlation

Hoarseness lasting more than 2 to 3 weeks in an adult, or more than 1 week in a child, needs the vocal folds examined.
Most hoarseness is laryngitis from a cold, but persistent hoarseness in a smoker or drinker suggests laryngeal cancer.
Hoarseness after thyroid, neck or chest surgery, or after intubation, suggests nerve or fold injury.
Hoarseness with trouble breathing or swallowing, or drooling in a small child, is an emergency.

Next step / Initial management

History (duration, smoking and alcohol, surgery, intubation, reflux, voice use) and neck exam; the folds must be seen by laryngoscopy.
Laryngitis from a cold: voice rest, hydration, stop smoking; no antibiotics.
Refer urgently to ENT (within about two weeks) for hoarseness over 3 weeks in a smoker or adult over 50, or with a neck lump, earache, dysphagia or weight loss.
Refer as an emergency (same day) for stridor, breathlessness or drooling, or new hoarseness with airway symptoms after thyroid surgery.
Unilateral palsy without a known cause: imaging of the nerve's full course from the skull base to the chest.

Test yourself

Think of the answer, then tap the question to see it.

After a total thyroidectomy a patient has stridor and breathlessness with a good voice. What happened?

Bilateral recurrent laryngeal nerve injury: both folds rest near the midline, so the voice can be fair but the airway is narrow. Airway emergency.

Why can left-sided vocal fold paralysis be the first sign of a lung cancer?

The left recurrent laryngeal nerve loops under the aortic arch in the chest, where a tumour or enlarged nodes can compress it.

Which laryngeal muscle is not supplied by the recurrent laryngeal nerve, and what does its loss cause?

The cricothyroid, supplied by the external branch of the superior laryngeal nerve; injury causes voice fatigue and loss of high pitch.

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Elsewhere in DurgiPedia

Fourth and sixth pharyngeal arches: the larynx and the vagus nerve

Connections

See it in 3D7

The structures of Durgical's 3D anatomy where it is found.

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Educational content; it does not replace a medical assessment and is not a clinical instruction. For a real case, follow current guidelines and specialist advice.

Sources: Anatomy, Head and Neck: Larynx (StatPearls (NCBI Bookshelf), 2023); Vocal Fold Paralysis (National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 2017); Hoarseness (MedlinePlus, US National Library of Medicine, 2024).

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