Final answer:
The esophagus is the structure that lies immediately posterior to the trachea, facilitating the passage of food from the pharynx to the stomach.
Step-by-step explanation:
The structure that lies immediately posterior to the trachea is the esophagus. The esophagus is the structure that lies immediately posterior to the trachea, facilitating the passage of food from the pharynx to the stomach. The trachea, also known as the windpipe, is a tube formed by stacked, C-shaped pieces of hyaline cartilage and connects the larynx to the lungs.
The trachea's fibroelastic membrane and trachealis muscle help maintain its structure and allow for flexibility during breathing. The esophagus serves as the passage for food from the pharynx to the stomach and is located posteriorly to the trachea, functioning separately from the respiratory system.