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The larynx, the vocal cords and the breathing tube: a guided tour

Why general anesthesia can leave you hoarse, and why awake surgery does not need to touch this delicate machinery.

Airway & voice · 6 min read · deep dive

Your larynx is about the size of a small plum, sits at the front of your neck, and does three jobs. A classic review lists them in priority order: protect the airway, allow breathing, and produce voice. Voice is the third job. Protection comes first, which is why a tiny drop of water on the cords can make you cough violently.

The architecture

  • Thyroid cartilage: the shield-shaped front wall. The bump you can feel (the “Adam’s apple”) is its front edge.
  • Cricoid cartilage: a signet-ring below it, the only complete ring in the airway.
  • Arytenoid cartilages: two small, mobile pyramids at the back. They rotate and slide to open and close the cords.
  • Epiglottis: a leaf-shaped lid that folds over the entrance when you swallow.
  • Vocal folds (cords): two bands of tissue stretching from the thyroid cartilage to the arytenoids. The gap between them is the glottis.
Vocal cords seen from aboveTwo simplified views of the vocal cords from above. Left: during quiet breathing the cords are apart, forming a V-shaped opening called the glottis. Right: during speaking the cords come together. front (thyroid cartilage)back (arytenoid cartilages)glottis (open) frontbackcords together BreathingSpeaking
Simplified view from above. The cords attach at the front to the thyroid cartilage and at the back to the small, movable arytenoid cartilages.

How voice happens

Air from the lungs passes between cords that are brought together; they vibrate and the sound is shaped by throat, tongue and lips. Small muscles and nerves (the recurrent laryngeal and superior laryngeal nerves) adjust tension and position with astonishing precision. CT studies of healthy adults show that laryngeal and pharyngeal dimensions vary with sex and height, which is one reason airway management is never one-size-fits-all.

What intubation actually is

  1. Under general anesthesia (usually with a muscle relaxant), the anesthesiologist uses a laryngoscope to lift the tongue and epiglottis and see the glottis.
  2. A flexible tube is passed between the open cords into the trachea.
  3. A soft cuff inflates just below the cords to seal the airway so a ventilator can breathe for you.

It is routine and extremely common, and anesthesiologists train for years to do it well. It is also a foreign object passing through the most sensitive part of your airway.

What can happen to the cords

  • Hoarseness and sore throat are common and usually short-lived. In 3,093 adults, 49% were hoarse on the day of surgery, 11% on day 3 and 0.8% on day 7. Older age and longer intubation predicted longer hoarseness.
  • Swelling: in a randomized study, vocal-cord swelling and increased laryngeal resistance appeared after an endotracheal tube but not after a laryngeal mask.
  • Arytenoid dislocation is rare (3 of 3,093, about 0.1%), and it is one cause of a voice that stays rough for longer.

Where awake surgery fits

For operations that can be done comfortably with local anesthesia, with or without light to moderate sedation, a breathing tube is often unnecessary, and your voice is never involved. That is not the right option for every operation or every patient: if an operation is long, extensive, or you are not suited to it, general anesthesia with a secure airway is the safer choice, and we will arrange it.

Questions people ask: Will I be able to talk during surgery? Usually yes, and that is useful. What if my airway needs help? That is exactly why an anesthesiologist, not a bystander, is beside you.

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References

  1. Sasaki CT, Isaacson G. Functional anatomy of the larynx. Otolaryngol Clin North Am. 1988;595-612. PMID 3054715
  2. Inamoto Y, Saitoh E, Okada S, et al. Anatomy of the larynx and pharynx: effects of age, gender and height revealed by multidetector computed tomography. J Oral Rehabil. 2015;670-677. PMID 25892610
  3. Yamanaka H, Hayashi Y, Watanabe Y, et al. Prolonged hoarseness and arytenoid cartilage dislocation after tracheal intubation. Br J Anaesth. 2009;452-455. PMID 19556269
  4. Tanaka A, Isono S, Ishikawa T, et al. Laryngeal resistance before and after minor surgery: endotracheal tube versus Laryngeal Mask Airway. Anesthesiology. 2003;252-258. PMID 12883396
  5. Xu R, Lian Y, Li WX. Airway complications during and after general anesthesia: a comparison, systematic review and meta-analysis of using flexible laryngeal mask airways and endotracheal tubes. PLoS One. 2016;e0158137. PMID 27414807