pharynx

pharynx, area of the gastrointestinal and respiratory tracts which lies between the mouth and the esophagus. In humans, the pharynx is a cone-shaped tube about 41/2 in. (11.43 cm) long. At its upper end, it is continuous with the mouth and nasal passages, and connects with the ears via the Eustachian tubes. The lower end of the pharynx is continuous with the esophagus (see digestive system). It is also connected to the larynx by an opening that is covered by the epiglottis during swallowing, thus preventing food from entering the trachea. The pharyngeal area is the embryological source of several important structures in vertebrates. For example, the breathing apparatus (gill pouches of fish and lungs of land animals) arises in this area (see respiration). In humans, the pharynx is particularly important as an instrument of speech: it functions with the various parts of the mouth to articulate the initial sounds produced in the larynx.

Inside of the throat, from the oral and nasal cavities (see mouth, nose) to the trachea and esophagus. It has three connected sections: the nasopharynx, at the back of the nasal cavity; the oropharynx, in the back of the oral cavity down to the epiglottis (a flap of tissue that closes off the larynx during swallowing); and the laryngopharynx, from the epiglottis to the esophagus. The oropharynx contains the palatine tonsils. The eustachian tubes connect the middle ears to the pharynx, allowing air pressure on the eardrum to be equalized. Disorders include pharyngitis, tonsillitis, and cancer.

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The pharynx (plural: pharynges) is the part of the neck and throat situated immediately posterior to (behind) the mouth and nasal cavity, and cranial, or superior, to the oesophagus, larynx, and trachea.

Functions

It was part of the digestive system and respiratory system of many organisms.

Because both food and air pass through the pharynx, a flap of connective tissue called the epiglottis closes over the trachea when food is swallowed to prevent choking or aspiration. In humans the pharynx is important in vocalization.

In persons with hayfever, oral allergy syndrome and related allergies, the pharynx is often a reaction site to allergens, with common symptoms including burning and itching.

Parts

The human pharynx is conventionally divided into three sections:

Oropharynx

The oropharynx lies behind the oral cavity. The anterior wall consists of the base of the tongue and the vallecula; the lateral wall is made up of the tonsil, tonsillar fossa, and tonsillar (faucial) pillars; the superior wall consists of the inferior surface of the soft palate and the uvula.

Nasopharynx

The nasopharynx lies behind the nasal cavity.

Postero-superiorly this extends from the level of the junction of the hard and soft palates to the base of skull, laterally to include the fossa of Rosenmuller.

The inferior wall consists of the superior surface of the soft palate.

Laryngopharynx

The laryngopharynx, also known as the hypopharynx, roughly corresponds to the levels between C4 to C6, it includes the pharyngo-esophageal junction (postcricoid area), the piriform sinus, and the posterior pharyngeal wall.

Like the oropharynx above it the hypopharynx serves as a passageway for food and air and is lined with a stratified squamous epithelium.

It lies inferior to the upright epiglottis and extends to the larynx, where the respiratory and digestive pathways diverge.

At that point, the laryngopharynx is continuous with the esophagus posteriorly. The esophagus conducts food and fluids to the stomach; air enters the larynx anteriorly. During swallowing, food has the "right of way", and air passage temporarily stops.

Additional images

References

• Human Anatomy and Physiology Elaine N. Marieb and Katja Hoehn, Seventh Edition.
• TNM Classification of Malignant Tumours Sobin LH & Wittekind Ch (eds)Sixth edition UICC 2002 ISBN 0-471-22288-7

See also

• Adenoid
• Eustachian tube
• Hyoid
• Keratosis pharyngis
• Larynx
• Tonsil
• Uvula

External links