Trachea

The trachea, also known as the windpipe, is a hollow tube made of hyaline cartilage, ligaments, and smooth muscle that conveys air between the larynx and the main bronchi. The trachea travels anterior to the esophagus into the thoracic cage.

The superior portion of the trachea is continuous with the larynx, and divides, or bifurcates, into the right and left main bronchi inferiorly. The length of the trachea consists of about 16-20 pieces of incomplete or “C” shaped rings of hyaline cartilage. They are called tracheal cartilage and keeps the trachea open at all times.

The epithelium that lines the lumen, or hollow inside of the trachea, produces mucus and contains cilia. Mucus functions to trap foreign particles and pathogens, while the tiny, hairlike projections of cilia move in a coordinated way to sweep mucus upward toward the pharynx where it can be swallowed or expelled. This cleaning process is known as mucociliary clearance.

The primary functions of the trachea include:

• Conducting air and holding the airway open
• Cleans air to protect the lungs from pathogens and foreign particles

Figure 1: The trachea. The left image shows the trachea with the bronchial tree. The right image shows a transverse cross-section of the trachea and esophagus.