During which phase does the bolus enter the pharyngoesophageal segment?

The pharyngeal phase is the correct answer because it is during this stage of swallowing that the bolus moves from the oropharynx into the esophagus. During the pharyngeal phase, various physiological processes are activated, such as the elevation of the larynx and closure of the vocal folds, which protect the airway, ensuring that the bolus moves down the esophagus efficiently and safely.

In contrast, the oral preparatory phase involves the initial manipulation of food in the mouth, while the oral transit phase is characterized by the movement of the bolus from the front to the back of the mouth in preparation for swallowing. The esophageal phase occurs after the bolus has already passed through the pharynx, where it travels down the esophagus to reach the stomach. Thus, the bolus specifically enters the pharyngoesophageal segment only in the pharyngeal phase of swallowing.