Human Anatomy
Larynx
Larynx anatomy for MBBS: cartilages, vocal folds, intrinsic muscles and laryngeal nerves, plus airway and nerve injury, mapped to NMC codes AN38.1 to AN38.3.
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Larynx
Larynx anatomy for MBBS: cartilages, vocal folds, intrinsic muscles and laryngeal nerves, plus airway and nerve injury, mapped to NMC codes AN38.1 to AN38.3.
The larynx chapter covers the cartilages, the vocal folds, the intrinsic muscles and the laryngeal nerves. It is the anatomical basis for voice change, the emergency airway and the effects of nerve injury during neck surgery.
High-yield: Larynx
- The larynx guards the airway and produces the voice, extending from the third to the sixth cervical vertebrae.
- Its cartilages are the thyroid, cricoid and epiglottis, which are single, and the arytenoid, corniculate and cuneiform, which are paired.
- The cricoid cartilage is the only complete ring in the airway and lies at the sixth cervical vertebra.
- The vocal folds are formed by the vocal ligaments and the vocalis muscle, stretched between the thyroid and arytenoid cartilages.
- The rima glottidis, the gap between the vocal folds, is the narrowest part of the adult larynx.
- All the intrinsic muscles of the larynx are supplied by the recurrent laryngeal nerve except cricothyroid.
- The cricothyroid is supplied by the external laryngeal nerve and tenses the vocal folds to raise the pitch.
- The posterior cricoarytenoid is the only muscle that opens the rima glottidis by abducting the vocal folds.
- Sensation above the vocal folds is carried by the internal laryngeal nerve, and below by the recurrent laryngeal nerve.
- Injury to one recurrent laryngeal nerve leaves the cord in a paramedian position, causing hoarseness.
- Bilateral recurrent laryngeal nerve injury can cause the cords to lie close together and obstruct the airway.
- The cricothyroid membrane is the site for an emergency airway in cricothyrotomy.
- Inhaled foreign bodies tend to lodge in the right main bronchus, but the larynx is where laryngospasm can block the airway.
- The internal laryngeal nerve pierces the thyrohyoid membrane to enter the larynx alongside the superior laryngeal vessels.
Laryngeal muscle actions and nerves
- **Posterior cricoarytenoid:** The only abductor. Opens the rima glottidis. Recurrent laryngeal nerve.
- **Cricothyroid:** Tenses the cords to raise pitch. External laryngeal nerve, the exception.
- **Other intrinsic muscles:** Adductors and tensors of the cords. All supplied by the recurrent laryngeal nerve.
- **Sensation:** Above the cords by the internal laryngeal nerve, below by the recurrent laryngeal nerve.
NMC competencies in this chapter
- **AN38.1:** Cartilages, joints and membranes of the larynx
- **AN38.2:** Intrinsic muscles, vocal folds and nerve supply of the larynx
- **AN38.3:** Applied anatomy of the larynx and laryngeal nerve injury
Frequently Asked Questions
Which muscle opens the vocal folds?
The posterior cricoarytenoid is the only abductor of the vocal folds; it opens the rima glottidis and is supplied by the recurrent laryngeal nerve.
Why does recurrent laryngeal nerve injury cause hoarseness?
It paralyses most intrinsic laryngeal muscles on that side, so the affected vocal fold cannot move normally and settles in a paramedian position, giving a hoarse voice.
Where is an emergency surgical airway made?
Through the cricothyroid membrane in a cricothyrotomy, a relatively safe and superficial site that avoids the thyroid gland and large vessels.
How does this chapter help in NEET-PG?
Laryngeal muscles, nerve supply and airway anatomy are core ENT and anaesthesia topics, so the larynx is directly high-yield for PG preparation.
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