The pharynx is responsible for adjoining the nasal cavity and the oral cavity to the larynx (which belongs to the respiratory system) and the esophagus (which belongs to the digestive system. It is approximately 13 centimeters long and is the shape of a funnel. Skeletal muscle creates the walls which provide structural support for the pharynx. The lumen is then lined with mucous membranes. The various lymphoid organs which are housed in the pharynx are known as the tonsils.


The pharynx is responsible for its share of both respiratory and digestive functions. In common terms, it is known as either the gullet or the throat. Vocalization sounds also resonate throughout the pharynx, creating an additional responsibility of speech assistance. The pharynx is segregated into three basic regions, based primarily on the function it performs and the area it serves.


Positioned above the mouth (which is the entryway point for nourishment) is the nasopharynx. This is the only entryway for air alone. The mouth serves both the digestive and the respiratory system. Situated directly behind the nasal cavity and just above the soft palate, this is the highest point of the pharynx. The uvula, which is the pendulum-like fixture that hangs above the opening of the esophagus, dangles from the middle lower segment of the soft palate. Eustachian tubes, which are the vital auditory tubes, adjoin the tympanic cavities with the nasopharynx.


Image: Pharynx

Adenoids, which are also known as the pharyngeal tonsils, are located in the nasal cavity along the posterior wall. When the human body swallows, the uvula and the soft palate rise up to prevent food from mistakenly going into the nasal cavity. As the uvula and the soft palate rise, they create a road block, forcing food down the esophagus. The sudden expulsion of air while swallowing liquid the uvula once again creates a road block, disallowing the liquid to enter the nasaopharynx and forcing the liquid out the nasal cavity.

The middle section of the nasaopharynx is positioned between the soft palate and the hyoid bone region. This middle region is known as the oropharynx. Air which has been inhaled as well as food or liquid which has been swallowed pass through this region on their way toward their destination.

The anterior wall of the oropharynx is created by the base of the tongue. Along the posterior lateral wall there are the palatine tonsils, and right along the base of the tongue one will find the lingual tonsils.

The lowest region of the pharynx can be found from the region of the hyoid bone down to the esophagus and larynx. This section is known as the laryngopharynx. The digestive system and the respiratory system become obviously two separate systems at the lower region of the laryngopharynx. Here, the food and liquid which has been swallowed is directed to the esophagus and the air which has been inhaled is directed to the anterior larynx.
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