Which structure in the throat operates as a flap to prevent food from entering the windpipe?

The epiglottis plays a crucial role in the process of swallowing by functioning as a protective flap that covers the entrance of the windpipe (trachea) during the act of swallowing. When you swallow, the epiglottis folds down over the larynx and closes off the air passage. This action prevents food and liquids from entering the windpipe, directing them instead into the esophagus where they travel down to the stomach. This mechanism is vital for ensuring that food does not enter the respiratory system, which could lead to choking or aspiration.

The esophagus is the tube that carries food from the throat to the stomach but does not have any flap-like functionality. The pharynx is the passageway that connects the nasal and oral cavities to the larynx and esophagus but does not specifically prevent food from entering the windpipe. The larynx contains the vocal cords and is involved in sound production; although it is located at the entrance of the airway, it does not function as a flap like the epiglottis does.