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Introduction
๐ค The larynx (voice box) is a dynamic organ in the anterior neck.
Functions:
- โก๏ธ Passageway for air (pharynx โ trachea)
- ๐ถ Sound production for speech
- ๐ก๏ธ Airway protection during swallowing
๐งฑ Cartilaginous Framework
- Unpaired Cartilages
- Thyroid cartilage: Largest; โAdamโs apple.โ Protects vocal cords.
๐ Clinical: Landmark for cricothyrotomy.
- Cricoid cartilage: Only complete ring; inferior boundary.
๐ Exam tip: Narrowest part of paediatric airway.
- Epiglottis: Leaf-shaped; covers laryngeal inlet on swallowing.
๐ Failure โ aspiration risk.
- Paired Cartilages
- Arytenoids: Control vocal fold movement/tension.
- Corniculates: Horn-shaped; sit on arytenoids.
- Cuneiforms: Support aryepiglottic folds.
๐ชข Ligaments & Membranes
- Extrinsic:
- Thyrohyoid membrane: Stabilises larynx to hyoid.
- Cricotracheal ligament: Connects cricoid โ trachea.
- Intrinsic:
- Quadrangular membrane: Upper boundary of ventricle.
- Cricothyroid ligament: Key in pitch control.
๐ Emergency airway access site.
๐๏ธ Internal Divisions of the Laryngeal Cavity
- Supraglottis: Epiglottis + vestibular (false) cords.
- Glottis: True cords + rima glottidis โ sound production.
- Subglottis: Below cords โ cricoid border โ trachea.
๐ช Musculature
- Intrinsic Muscles (fine control of cords)
- Cricothyroid: Tenses cords โ pitch (๐ต).
Nerve: external branch, SLN.
- Posterior cricoarytenoid: Only abductor โ opens cords.
๐ Paralysis = stridor.
- Lateral cricoarytenoid & interarytenoids: Adduct cords โ phonation.
- Thyroarytenoid (vocalis): Modulates mass/tension โ tone quality.
- Extrinsic Muscles (position larynx for swallowing/speech):
e.g., thyrohyoid, sternohyoid, omohyoid.
๐ฉธ Blood Supply & Innervation
- Arteries:
- Superior laryngeal artery (from superior thyroid).
- Inferior laryngeal artery (from inferior thyroid).
- Nerves:
- Superior laryngeal nerve (SLN): Internal = sensation supraglottis; External = motor โ cricothyroid.
- Recurrent laryngeal nerve (RLN): Motor to all other intrinsic muscles; sensory to subglottis.
๐ Clinical: Unilateral RLN palsy = hoarse voice; bilateral = airway obstruction.
โ๏ธ Clinical Relevance
- ๐ฃ๏ธ Vocal cord paralysis: RLN injury (thyroid surgery, lung cancer). Hoarseness, aspiration, stridor.
- ๐คง Laryngitis: Inflammation โ hoarse/absent voice.
- ๐ ๏ธ Airway procedures: Cricothyrotomy, intubation, tracheostomy โ rely on landmarks.
- ๐งช Laryngeal cancer: Often presents with persistent hoarseness โ needs early ENT referral.
๐ Key Exam Pearls
- Posterior cricoarytenoid = only abductor.
- RLN supplies all intrinsic muscles except cricothyroid.
- Subglottic narrowing = paediatric airway obstruction site.
- Glottis = main sound source for phonation.
โ
Conclusion
The larynx is a finely tuned organ balancing respiration, phonation, and protection.
Understanding its cartilages, muscles, and nerve supply is essential for safe surgical practice, airway management, and recognising pathology.