What is the structural composition of the trachea's back?

The correct structural composition of the back of the trachea involves the presence of smooth muscle. The trachea is a tubular structure that connects the larynx to the bronchi of the lungs, and it is lined with cartilage to maintain its open shape. However, it is not entirely made up of cartilage; rather, the posterior aspect of the trachea is supported by smooth muscle, known as the trachealis muscle. This smooth muscle allows for flexibility and the ability to adjust the diameter of the trachea during breathing.

This muscle arrangement is crucial because it enables the trachea to collapse slightly during swallowing as the esophagus expands, allowing for efficient function without compromising the airway. This unique structural organization highlights the importance of smooth muscle in the trachea's functionality, differentiating it from the more rigid cartilage that comprises the anterior and lateral walls of the trachea.