24.4 The Trachea

• • The trachea starts at the cricoid cartilage in the neck, enters the mediastinum, and ends at its division into the right and left bronchi. It sits anterior to the esophagus and is lined with a typical respiratory epithelium.
• The trachea or windpipe is a tough, flexible tube
• This respiratory epithelium sits on a layer of loose connective tissue called the lamina propria
• The combination of epithelium and lamina propria is an example of a mucosa or mucous membrane
• A layer of connective tissue, the submucosa, is deep to the lamina propria
• Deep to the submucosa, the trachea contains 15-20 tracheal cartilages
• Elastic annular ligaments attach each tracheal cartilage to its adjacent cartilages
• An elastic ligament and a band of smooth muscle, the trachealis, connect the open ends of each tracheal cartilage
• SUMMARY

  • The trachea (windpipe) extends from the sixth cervical vertebra to the fifth thoracic vertebra. The submucosa contains C shaped tracheal cartilages that stiffen the tracheal walls and protect the airway. The posterior tracheal wall can distort to permit large masses of food to move along the esophagus.
• The cartilages reinforcing the trachea are C-shaped rather than complete rings. How does this shape help with swallowing while still protecting the trachea?

  The tracheal cartilages are C-shaped to allow room for esophageal expansion when large masses of food or liquid are swallowed.
• What type of epithelium can be observed in the trachea?

  The trachea has a typical respiratory epithelium, which is pseudostratified, ciliated, columnar epithelial cells.
• How are tracheal cartilages involved in airflow?

  Tracheal cartilages prevent the overexpansion or collapse of the airways during respiration, thereby keeping the airway open and functional.