tracheabronchial

Tracheobronchial refers to the airway passage system that includes the trachea and its subsequent branches into the bronchi and smaller bronchi within the lungs. This tree conducts air from the larynx to the alveolar regions and provides a conduit for filtration, humidification, and warming of inspired air. The term is commonly used to describe anatomical and physiological aspects of the central airways as a unit.

Anatomy: The trachea begins anterior to the esophagus and descends to the level of the sternal angle, where it divides into the right and left main bronchi at the carina. The right main bronchus is shorter, wider, and more vertical than the left, and it gives rise to three lobar bronchi, while the left gives two. Each main bronchus branches into lobar (secondary) bronchi, which further divide into segmental (tertiary) bronchi, and so on through progressively smaller bronchi that still contain cartilage in their walls. The conducting portion is lined by pseudostratified ciliated columnar epithelium with goblet cells and submucosal glands, enabling mucociliary clearance. Airway smooth muscle becomes more prominent in the smaller bronchi and bronchioles.

Function and physiology: The tracheobronchial tree filters inspired air, adds moisture, and heats it. The mucociliary escalator traps particles and pathogens and clears them toward the pharynx. Bronchial glands secrete mucus; airway smooth muscle regulates caliber, modulating airflow in response to autonomic input and inflammatory mediators.

Clinical relevance: Disorders affecting the tracheobronchial tree include acute tracheobronchitis, bronchitis, asthma, chronic obstructive pulmonary disease, bronchiectasis, tracheobronchomalacia, and tumors. Bronchoscopy and CT are common evaluation methods; treatment may involve bronchodilators, antibiotics, or airway clearance therapies.

Embryology: The tracheobronchial tree develops from the foregut as the respiratory diverticulum, undergoing branching morphogenesis to form the complete airway network.