Behind the oral and nasal cavities and near the voice box is the pharynx. The pharynx is divided into three zones: behind the nasal cavity it is called the nasopharynx, behind the mouth it is the oropharynx, and around the top of the voice box, the laryngopharynx. It is the latter two that we generally call the throat. The Internal nares are the channels at the back of the nasal cavity that open into the nasopharynx. The nasopharynx extends from the top of the pharynx down to the border of the soft palate on the roof of the mouth. Below that point and behind the mouth, it is called the oropharynx. The tag of flesh hanging from the posterior edge of the soft palate, the uvula, marks the border between the mouth and oropharynx.
The oropharynx belongs to both the respiratory and the digestive systems, for air, liquid, and food pass through it. It ends at the level of the hyoid bone and epiglottis, above the voice box, where the laryngopharynx begins. In the laryngopharynx, digestive and respiratory passages separate. The esophagus carries food to the stomach, while the trachea, or windpipe, carries air to the lungs. The epiglottis folds down to cover the passageway into the larynx during swallowing, thus preventing food or liquid from entering the windpipe.