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Portrait of Vocal cords

Anatomy · Head, neck & teeth

Vocal cords

The sound-producing folds of the larynx

Larynx · glottis

Two pearly-white folds of mucous membrane and muscle that stretch across the airway inside the larynx, from the thyroid cartilage at the front to the arytenoid cartilages behind. The slit between them is the glottis. Air pushed up from the lungs sets their edges vibrating to make the voice; muscles moving the arytenoids open them for breathing, close them for speech and swallowing, and alter their tension for pitch.

How to spot them

  • ▸Two white bands seen from above on laryngoscopy, meeting in a V at the front and separated by a triangular gap
  • ▸Lie below a pair of pink 'false' folds, the vestibular folds
  • ▸Attach in front to the inner surface of the thyroid cartilage and behind to the arytenoids
  • ▸Longer in men (about 17–25 mm) than in women (about 12.5–17.5 mm)

What to know

First seen in a living person in 1854 by a Spanish singing teacher in London, using a dentist's mirror and sunlight (1854)

Manuel García, who invented the laryngoscope and saw his own vocal cords

The one muscle of the larynx that pulls them apart, and its failure on both sides can threaten breathing

The posterior cricoarytenoid muscle, the only abductor of the vocal cords

A nerve that loops under the aortic arch on the left and the subclavian artery on the right supplies all but one of the muscles that move them

The recurrent laryngeal nerve; damage causes hoarseness

A loose, gelatinous space beneath the surface layer that allows the edge to ripple, and can swell in heavy smokers

Reinke's space and Reinke's oedema

Average pitch of about 100–120 hertz in men and about 200–220 in women, because they are longer and thicker in men

The fundamental frequency of the voice, set by the length and mass of the vocal cords

Bright white because they are covered by stratified squamous epithelium with no blood vessels of their own

The true vocal cords, pearly white, unlike the pink false cords

A pair of pink folds above them, which do not vibrate in normal speech, are commonly called their 'false' partners

The vestibular (ventricular) folds — 'false vocal cords'

Key ideas

  • In the myoelastic-aerodynamic theory, air pressure blows the closed folds apart, elasticity and the Bernoulli effect snap them shut again, and the cycle repeats 100 to 1,000 times a second.
  • Pitch depends on tension and length, adjusted by cricothyroid (which tightens) and thyroarytenoid or vocalis (which relaxes and shortens), while loudness depends on air pressure.

Quick-fire facts

  • •All intrinsic muscles of the larynx are supplied by the recurrent laryngeal nerve except cricothyroid, which is supplied by the external branch of the superior laryngeal nerve
  • •The left recurrent laryngeal nerve hooks beneath the aortic arch beside the ligamentum arteriosum; the right hooks beneath the right subclavian artery
  • •The gap between the true folds is the rima glottidis, or glottis
  • •Layered structure: epithelium, then a three-layered lamina propria (the superficial layer being Reinke's space), then the vocalis muscle
  • •Fundamental frequency averages about 100–120 Hz in men and 200–220 Hz in women; voice pitch drops about an octave in boys at puberty
  • •Manuel García's paper on his observations was presented to the Royal Society in 1855
  • •Laryngitis is inflammation of the larynx; most cases are viral and settle within a week or two
  • •Vocal nodules, 'singer's nodes', form on the edges from overuse

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Sources