Food is prevented from entering the trachea during swallowing by the

The esophageal sphincter does not prevent food from entering the trachea. There are two esophageal sphincters, the upper one prevents air from entering the esophagus during respiration, and the lower one prevents stomach acid and digested food from backing up into the esophagus from the stomach. Neither of these sphincters have a role in preventing food from entering the trachea.

The glottis is the opening between the vocal cords that leads to the trachea. While it does play a role in the regulation of airflow to and from the lungs, the glottis itself does not prevent food or drink from entering the trachea during swallowing. That role is performed by the epiglottis, which covers the glottis during swallowing.

The pharynx, or throat, is the passageway leading from the mouth and nasal cavity to the esophagus and larynx. While it is involved in the process of swallowing, it does not prevent food from entering the trachea. Rather, it serves as a pathway for both food (going to the esophagus) and air (going to the trachea).