Which structure prevents food from entering the trachea during swallowing?

The epiglottis is a flap of tissue located at the base of the tongue that plays a crucial role in the swallowing process. When a person swallows, the epiglottis folds down over the larynx, effectively sealing off the trachea (the windpipe). This action prevents food and liquids from entering the airway, directing them instead into the esophagus which leads to the stomach. The epiglottis is essential for protecting the respiratory system from aspiration, which can lead to choking or respiratory infections.

In contrast, the other structures listed serve different functions. The larynx is involved in sound production and also acts as a passageway for air. Adenoids are related to the immune response and help to filter pathogens that may enter through the nasal cavity, but they do not directly prevent food from entering the trachea. Lastly, the uvula hangs down at the back of the throat and helps in the swallowing process by aiding in the closure of the nasal passages, but it does not directly cover the trachea during swallowing as the epiglottis does.