26.3 : 咽喉

The pharynx or throat is about a 13 cm long tube extending from the internal nares down to the cricoid cartilage of the larynx.

It can be divided into the nasopharynx, oropharynx, and laryngopharynx.

The nasopharynx is the upper segment located behind the nasal cavity, extending to the soft palate.

It is lined with ciliated pseudostratified columnar epithelium, which helps propel the mucus downward.

The posterior wall of the nasopharynx contains the pharyngeal tonsil that traps dust and pathogens from the inhaled air.

The oropharynx, the middle section, is a shared pathway for air, food, and liquid that opens into the throat through the fauces.

It has two palatine tonsils embedded in lateral walls and two lingual tonsils posterior to the oral cavity.

The laryngopharynx, the lowest part, opens into the esophagus posteriorly and the larynx anteriorly at its lower end.

Both the oropharynx and laryngopharynx are lined with nonkeratinized stratified squamous epithelium to avoid abrasion from the food particles.