What Are the Functions of the Nasal & Oral Pharynx for Breathing?
The pharynx is a muscular funnel that extends from the back of the nose to the larynx, or voice box. It can be divided into three parts, from superior to inferior: the nasopharynx, the oropharynx and the laryngopharynx. The two superior parts aid in breathing.
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Nasopharynx
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The nasal pharynx, or nasopharynx, begins behind the choana, or posterior nostril (the open space at the far back of the nasal cavity before it turns down into the lungs). It includes the pharyngeal tonsil and the auditory tubes that open to the middle ear.
Oropharynx
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The oral pharynx, or oropharynx, begins at the space between the soft palate and the roof of the tongue, and extends down to the level of the hyoid bone, which is under the tongue. It contains the palatine tonsils (visible in the back of the throat) and lingual tonsils, as well as the epiglottis, the flap that keeps food from coming down the windpipe during swallowing.
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Air Travel in the Nasopharynx
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Air that is inhaled from the nose has to make a 90-degree turn in the nasopharynx, which is difficult for large particles in the air. These heavy foreign particles usually travel straight into the back wall of the throat, crashing into and sticking to the pharyngeal tonsil.
Air Travel in the Oropharynx
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As air passes through the oropharynx, the epiglottis remains open. When the epiglottis flaps close, it shuts off the larynx and allows food and drink to pass down the esophagus without causing choking.
Passage Linings
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The nasopharynx takes in only air, and is lined by cells that secrete mucus. This mucus keeps the air we breathe moist and traps any foreign particles, and the mucus is eventually digested by the stomach. The oropharynx and laryngopharynx take in both food and air, and are lined by smooth tissue that resembles our outer skin, only softer. The cells of this tissue, like skin cells, can take a lot of abuse and flake off, which helps food to pass down without injuring the throat.
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References
- Photo Credit Medline Plus, Gray's Anatomy
