Final answer:
The pharynx is the space at the back of the mouth leading to the airway or the esophagus, serving as a pathway for both air and food.
Step-by-step explanation:
The pharynx is a tubular structure that connects the nasal cavity and the back of the mouth to the esophagus and larynx, serving as a passageway for both air and food. When food enters the pharynx, involuntary muscle contractions ensure that the air passageway is closed off, directing food toward the esophagus. The pharynx is made up of three sections: the nasopharynx, which is involved in breathing and speech, the oropharynx, and the laryngopharynx, which is used for both breathing and digestion. The laryngopharynx connects inferiorly to the esophagus and anteriorly to the larynx, allowing air to flow into the bronchial tree.