The walls of the pharynx are attached to the margins of the nasal cavity, oral cavity, and larynx. Based on the attachments, the pharynx is subdivided into three regions:
- Nasopharynx: It is situated in the space between the back of the nose and soft palate. It is continuous with the nasal cavity and forms the upper part of the respiratory system. It plays an important role in transferring air from the nose to the larynx. The soft palate separates the nasopharynx from the oropharynx. The adenoid tissue in the nasopharynx is the lymphoid tissue that helps fight infections entering through the nasal epithelium or lining. The Eustachian tube connects the middle ear to the nasopharynx. The tube regulates the pressure in the middle ear and helps drain our segregation in the ear.
- Oropharynx: It is a part of the pharynx located at the back of the mouth. The muscles and structures in the oropharynx allow us to breathe while chewing or manipulating material in the oral cavity. Therefore, we can talk when we eat, or we can breathe even while eating. The tonsils are located between the pharyngeal pillars. The tonsils are called as gatekeepers. Their function is to help fight infections that enter through the mouth or nose. They contain a collection of white cells.
- Laryngopharynx: It extends from the front of the epiglottis to the top of the esophagus at the level of base of the neck. A structure known as the piriform fossa is present here that forms channels directing solids and liquids from the oral cavity to the esophagus. Its main function is to regulate the entry of air to the lungs and food to the esophagus.
Main functions of the pharynx
Following are the main functions of the pharynx:
- The pharynx serves both respiratory and digestive functions.
- It is a 5-inch-long cylindrical tube that involves the passage of food and air into its appropriate chambers.
- The connection between the oral and nasal regions enables us to breathe through nose and mouth.
- The pharyngotympanic tube (Eustachian tube) connecting the middle ear to the pharynx equalizes the air pressure in the ear and drains fluid from the ear, preventing ear infections.
- It plays an important role in phonation (speech). It provides an enclosed space that allows the speech muscles to initiate sound and pronounce syllables better.
- The lining of the pharynx secretes mucus to lubricate the pharynx and helps in smooth propulsion of food down to the esophagus and reduce throat irritation.
- It provides drainage to the nose, oral cavity, and middle ear.
- Specialized lymphoid tissue (adenoids and tonsils) fights off the invading foreign cells, toxins, bacteria, and viruses.
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