Bronchi

The air passages that branch from the trachea and lead directly to the lungs.

Bronchi are the two main airways that emerge from the trachea, which is the windpipe of the respiratory system. Each bronchus (singular of bronchi) bifurcates into several smaller branches called bronchioles, which penetrate deeper into the lungs. These structures play a crucial role in conducting air to and from the lungs, facilitating both respiratory and exchange processes.

Terminologia Anatomica

bronchi

System

Respiratory system

Function

The primary function of the bronchi is to provide a passageway for air to travel in and out of the lungs. Upon inhalation, air enters through the trachea and divides into the right and left main bronchi, which lead to the respective lungs. The bronchi are lined with mucus-secreting cells and cilia, which trap dust, pathogens, and other particulates, protecting the delicate lung tissue. By continuously filtering and humidifying the air, the bronchi help to ensure that oxygen reaches the alveoli, the tiny air sacs where gas exchange occurs. Additionally, they play a role in regulating airflow; the smooth muscle surrounding the bronchi can contract or relax to control the size of the air passages, making breathing more efficient.

Location

The bronchi are located in the thoracic cavity, specifically situated within the mediastinum region of the chest. After the trachea descends from the throat, it divides into the right and left main bronchi at approximately the level of the T5 thoracic vertebra, just above the lungs. The right bronchus is shorter, wider, and more vertical than the left bronchus, which has a slightly longer and angulated course, accommodating the heart's placement on the left side of the thorax. As the bronchi enter the lungs, they further subdivide into secondary (lobar) bronchi, which correspond to the lung lobes, and eventually into multiple tertiary (segmental) bronchi, further branching down into the bronchioles, leading to the alveoli.

Did You Know?

The right main bronchus is more prone to obstruction because it is straighter and wider than the left bronchus.
The cilia lining the bronchi move in a coordinated fashion to transport mucus out of the lungs to keep the airways clear.
The bronchi contain hyaline cartilage rings that provide structural support, ensuring they remain open as air flows through.
Inflammation or obstruction of the bronchi can lead to significant respiratory issues, including bronchitis and asthma.