bronhii

Bronhii is a term used in some linguistic and historical contexts to refer to the bronchial tubes, particularly the main divisions of the airway that comprise the bronchial tree. In modern English anatomy, the standard plural form is bronchi; bronhii may appear in older texts or in non-English sources as an alternate or Latinized usage. The concept generally encompasses the main bronchi and their subsequent branches that conduct air to the lungs.

Anatomy and distribution

The bronhii (main bronchi) arise from the trachea at the carina and consist of the right and left bronchus. The right main bronchus is typically shorter, wider, and more vertical than the left, and it rapidly branches into three lobar (secondary) bronchi for the right lung’s three lobes. The left main bronchus generally gives rise to two lobar bronchi for the two left lung lobes. Each main bronchus then subdivides into smaller segmental (tertiary) bronchi that supply lung segments, continuing into progressively smaller airways.

Structure

The walls of the main bronchi are lined with pseudostratified ciliated columnar epithelium containing goblet cells and supported by cartilage rings that gradually become plates in smaller bronchi. A submucosal layer contains glands, and smooth muscle lies between the mucosa and cartilage. As the bronchi branch into smaller airways, cartilage diminishes and the epithelium becomes simpler, transitioning toward the bronchioles.

Function and clinical relevance

The bronhii conduct, condition, and defense air entering the lungs by warming, humidifying, and filtering inspired air and supporting mucociliary clearance. Inflammation or infection of these airways, such as bronchitis, and obstructions or structural diseases affecting the bronhii contribute to a range of respiratory conditions, including bronchiectasis and COPD. Imaging and bronchoscopy commonly assess the bronchial tree in clinical practice.

Development

During embryogenesis, the bronhii derive from the foregut endoderm, with surrounding mesenchyme forming cartilage, smooth muscle, and glands that shape the bronchial walls.