MedCourseFinder

Structure

Trachea

Not medically reviewed · Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The trachea is a flexible, cartilage-supported airway about 10 to 12 cm long that connects the larynx to the main bronchi. It is kept patent by C-shaped cartilaginous rings.

Terminologia Anatomica (Latin): Trachea · Open in the 3D atlas

Location

It begins at the lower border of the cricoid cartilage (about C6), descends through the neck and the superior mediastinum, and divides at the carina into the two main bronchi at about T4 to T5. The level of the bifurcation varies with respiration, posture and age.

Structure

The wall contains 16 to 20 incomplete hyaline cartilage rings, closed posteriorly by the trachealis (smooth muscle) and fibroelastic membrane. The lining is ciliated pseudostratified columnar epithelium with goblet cells. In the neck the isthmus of the thyroid lies in front of tracheal rings 2 to 4, and the oesophagus lies behind; in the thorax the aortic arch lies to the left and the right brachiocephalic trunk in front.

Blood supply

The cervical part is supplied mainly by the inferior thyroid arteries, and the thoracic part by bronchial arteries. Venous blood drains to the inferior thyroid veins and the brachiocephalic venous system.

Innervation

Parasympathetic and sensory fibres come from the vagus and recurrent laryngeal nerves; sympathetic fibres arise from the sympathetic trunks. The mucosa is rich in cough-reflex afferents, particularly at the carina.

Function

The trachea conducts air between the larynx and the bronchi, warms and humidifies it, and clears particles by the mucociliary escalator. Its rings resist collapse during inspiration while the trachealis permits changes in calibre, for example during cough.

Clinical correlations

Endotracheal intubation and tracheostomy (usually through the upper tracheal rings, below the cricoid) rely on its anatomy; the thyroid isthmus and vessels lie close by. Inhaled foreign bodies enter the right main bronchus more often. Tracheal compression by goitre or mediastinal masses, and tracheal stenosis after prolonged intubation, can narrow the airway.

Common exam points

  • Length about 10 to 12 cm, from C6 (lower border of cricoid) to the carina at about T4-T5; the level varies with respiration.
  • 16 to 20 C-shaped hyaline cartilages, with the trachealis muscle closing the posterior gap.
  • Relations: thyroid isthmus over rings 2 to 4, oesophagus posterior, aortic arch on the left.
  • Mucosa: ciliated pseudostratified columnar epithelium with goblet cells (mucociliary clearance).
  • Foreign bodies enter the right main bronchus more often than the left.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Netter FH. Atlas of Human Anatomy. Elsevier — Tier 3 (textbook)

References are listed only where the article cites them. See the sources page for the full policy. How sources are chosen and credited

Back to the index