AN38.1-3 | Larynx — Summary & Reflection

REFLECT

KEY TAKEAWAYS

Larynx — Key Points:

1. Cartilages: thyroid (largest, Adam's apple), cricoid (only complete ring), epiglottis (elastic, protects airway); paired: arytenoids (vocal + muscular processes), corniculate, cuneiform
2. Compartments: vestibule (supraglottis) → ventricle → subglottis; glottis = vocal cords + rima glottidis
3. Narrowest point: rima glottidis (adult); subglottis/cricoid ring (child) — explains croup stridor
4. Intrinsic muscles: all = RLN EXCEPT cricothyroid (external SLN); PCA = ONLY abductor; LCA + arytenoids = adductors; cricothyroid = tenses/lengthens cord (pitch)
5. RLN course: right loops under subclavian; left loops under aortic arch (ligamentum arteriosum) — both ascend in tracheo-oesophageal groove → enter larynx posterior to cricothyroid joint
6. Unilateral RLN injury: hoarseness (cord paramedian); bilateral: stridor + respiratory failure → emergency tracheostomy
7. Non-recurrent RLN (right, 0.5–1%): direct transverse course; associated with aberrant right subclavian artery; surgical trap
8. Lymphatics: glottis = almost none (T1 glottic = best prognosis); supraglottis = rich, bilateral (early N+)
9. Croup: subglottic oedema encircled by inelastic cricoid → stridor; steeple sign on X-ray; treat with dexamethasone
10. Emergency airway: cricothyrotomy = cricothyroid membrane (between thyroid and cricoid cartilages)