Trachea Anatomy: Structure, Key Components, and Function

Overview

The trachea (windpipe) is a 10–12 cm fibroelastic tube connecting the larynx (C6) to the carina (T4/T5), where it bifurcates into left and right main bronchi.

Wall Structure

• 16–20 C-shaped hyaline cartilage rings (anterior/lateral) – prevent collapse during inspiration.
• Trachealis muscle (smooth muscle) – bridges posterior gap; contracts during coughing to narrow lumen, increase airflow velocity.
• Mucosa: Pseudostratified ciliated columnar epithelium with goblet cells → mucociliary escalator traps/clears particles.
• Adventitia: Connective tissue anchoring to surrounding structures.

Key Intraluminal/Adjacent Structures

• Vocal cords (true): In larynx, superior to trachea – phonation.
• Epiglottis: Leaf-shaped elastic cartilage; folds over laryngeal inlet during swallowing – prevents aspiration.
• Carina: Keel-like ridge at bifurcation; sensitive cough receptor zone.
• Thyroid gland: Isthmus overlies 2nd–4th tracheal rings.
• Recurrent laryngeal nerves: Run in tracheoesophageal grooves – injury risk in thyroid surgery.
• Esophagus: Posterior to trachea; shared wall in places.

Clinical Correlates

• Tracheomalacia: Cartilage weakness → expiratory collapse → stridor, cough.
• Tracheal stenosis: Post-intubation, trauma, granulomatosis with polyangiitis.
• Tracheoesophageal fistula: Congenital or acquired (malignancy, intubation).
• Intubation: Tube passes through vocal cords, cuff sits below cords, above carina.

Function Summary

Conducts air, conditions it (warm, humidify, filter), protects lower airway via mucociliary clearance and cough reflex. Cartilage rings maintain patency during pressure swings.