trachea

The trachea, commonly known as the windpipe, is a rigid but flexible air conduit that lies anterior to the esophagus in the neck and upper chest. It extends from the inferior border of the larynx (about the level of the cricoid cartilage, C6) to the carina at roughly the level of the thoracic inlet (T4/T5), where it divides into the right and left main bronchi.

Anatomically, the trachea consists of 16 to 20 C-shaped hyaline cartilage rings that provide structural support and keep the airway open. The open posterior aspect is bridged by smooth muscle (the trachealis) and connective tissue, allowing slight constriction and expansion. The walls are lined by a pseudostratified ciliated columnar epithelium with goblet cells, resting on a basement membrane and a vascularized lamina propria. The submucosa contains seromucous glands that contribute to mucus production.

Functions include conducting inhaled air to the lungs, humidifying and warming the air, and clearing mucus and debris via the mucociliary escalator, in which cilia move mucus toward the pharynx for swallowing.

Clinical notes and development: the trachea can be affected by trauma, infection, tumors, or congenital conditions. Prolonged intubation or inflammation can lead to tracheal stenosis, while the Carina is a sensitive region that can trigger cough reflexes. Tracheal development derives from the foregut endoderm with successive formation of the tracheoesophageal septum. Tracheostomy typically lies in the anterior wall between the second and third tracheal rings, just below the cricoid cartilage.