View source for Pharynx

__NOTOC__
{{SI}}
{{CMG}}

==Overview==
The '''pharynx''' (plural: '''pharynges''') is an organ found in vertebrates and invertebrates, though the structure is not universally the same across the species. In [[human]]s the pharynx is part of the [[Human digestive system|digestive system]] and also of the [[conducting zone]] of the [[respiratory system]]. (The conducting zone also includes the [[nose]], [[larynx]], [[trachea]], [[bronchus|bronchi]], and [[bronchiole]]s, and their function is to filter, warm, and moisten air and conduct it into the [[lung]]s.<ref>{{Cite book|title = Respiratory Syster|publisher = Benjamin Cummings (Pearson Education, Inc)|year = 2006|isbn = |location = |pages = 1|url = http://www.kean.edu/~jfasick/docs/Spring%20Semester%20Lectures%20Chapt.%2016-28/Chapter%2022a.pdf|chapter = |format = PDF}}</ref>) The pharynx makes up the part of the [[throat]] situated immediately posterior to the [[nasal cavity]], posterior to the [[Human mouth|mouth]] and superior to the [[esophagus]] and [[larynx]]. The human pharynx is conventionally divided into three sections: the nasopharynx, the oropharynx and the laryngopharynx. It is also important in [[Speech production|vocalization]].

There are two sets of [[pharyngeal muscles]] that act upon the pharynx. These are arranged as an inner layer of longitudinal [[muscle]]s and an outer circular layer.

==Structure==
=== Nasopharynx ===
The upper portion of the pharynx, the nasopharynx, extends from the base of the [[skull]] to the upper surface of the [[soft palate]].<ref>Clinical Head and Neck and Functional Neuroscience Course Notes, 2008-2009, [[Uniformed Services University of the Health Sciences]] School of Medicine, Bethesda, Maryland</ref> It includes the space between the [[choana|internal nares]] and the soft palate and lies above the oral cavity. The [[adenoids]], also known as the pharyngeal tonsils, are [[lymphoid tissue]] structures located in the posterior wall of the nasopharynx. [[Waldeyer's tonsillar ring]] is an annular arrangement of lymphoid tissue in both the nasopharynx and oropharynx.
[[Polyp_(medicine)|Polyps]] or [[mucus]] can obstruct the nasopharynx, as can congestion due to an upper respiratory infection. The [[eustachian tubes]], which connect the middle ear to the pharynx, open into the nasopharynx. The opening and closing of the eustachian tubes serves to equalize the barometric pressure in the middle ear with that of the ambient atmosphere.

The anterior aspect of the nasopharynx communicates through the [[choanae]] with the nasal cavities. On its lateral walls are the [[pharyngeal ostium|pharyngeal ostia]] of the [[auditory tube]], somewhat triangular in shape, and bounded behind by a firm prominence, the [[torus tubarius]] or cushion, caused by the medial end of the cartilage of the tube that elevates the [[mucous membrane]]. Two folds arise from the cartilaginous opening:
* the [[salpingopharyngeal fold]], a vertical fold of mucous membrane extending from the inferior part of the torus and containing the [[salpingopharyngeus muscle]]
* the [[salpingopalatine fold]], a smaller fold extending from the superior part of the torus to the palate and containing the [[levator veli palatini]] muscle. The [[tensor veli palatini]] is lateral to the levator and does not contribute the fold, since the origin is deep to the cartilaginous opening.

Behind the opening of the [[auditory tube]] is a deep recess, the [[pharyngeal recess]] (also referred to as the ''fossa of Rosenmüller''). On the posterior wall is a prominence, best marked in childhood, produced by a mass of lymphoid tissue, which is known as the [[pharyngeal tonsil]]. Superior to the pharyngeal tonsil, in the midline, an irregular flask-shaped depression of the mucous membrane sometimes extends up as far as the basilar process of the [[occipital bone]], this is known as the ''pharyngeal bursa''.

=== Oropharynx ===
The oropharynx lies behind the oral cavity, extending from the [[uvula]] to the level of the [[hyoid bone]]. It opens anteriorly, through the [[isthmus faucium]], into the [[Human mouth|mouth]], while in its lateral wall, between the [[palatoglossal arch]] and the [[palatopharyngeal arch]], is the [[palatine tonsil]].<ref>http://teachmeanatomy.info/neck/viscera/pharynx/</ref> The anterior wall consists of the base of the tongue and the [[epiglottic 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. Because both [[food]] and [[Earth's atmosphere|air]] pass through the pharynx, a flap of connective tissue called the [[epiglottis]] closes over the [[glottis]] when food is swallowed to prevent [[Pulmonary aspiration|aspiration]]. The oropharynx is lined by non-keratinised squamous stratified epithelium.

The ''HACEK'' organisms (''[[Haemophilus|'''H'''aemophilus]], [[Actinobacillus|'''A'''ctinobacillus actinomycetemcomitans]], [[Cardiobacterium hominis|'''C'''ardiobacterium hominis]], [[Eikenella|'''E'''ikenella corrodens]], [[Kingella|'''K'''ingella]]'') are part of the normal oropharyngeal flora, which grow slowly, prefer a carbon dioxide-enriched atmosphere, and share an enhanced capacity to produce [[endocardial]] infections, especially in young children.<ref name="pmid18087053">{{cite journal |vauthors=Morpeth S, Murdoch D, Cabell CH, etal |title=Non-HACEK gram-negative bacillus endocarditis|journal=Ann. Intern. Med.|volume=147|issue=12|pages=829–35|date=December 2007|pmid=18087053|doi=10.7326/0003-4819-147-12-200712180-00002}}</ref> ''[[Fusobacterium]]'' is a pathogen.<ref name="ludlam2004">{{cite journal|title=Real-time PCR investigation into the importance of ''Fusobacterium necrophorum'' as a cause of acute pharyngitis in general practice |vauthors=Aliyu SH, Marriott RK, Curran MD, etal |journal=J Med Microbiol|volume=53|year=2004|pages=1029&ndash;35|doi=10.1099/jmm.0.45648-0|pmid=15358827|issue=Pt 10}}</ref>

===Laryngopharynx===
The laryngopharynx, ([[Latin]]: ''pars laryngea pharyngis''), also known as hypopharynx, is the [[Caudal (anatomical term)|caudal]] part of the pharynx; it is the part of the throat that connects to the esophagus. It lies inferior to the epiglottis and extends to the location where this common pathway diverges into the respiratory ([[larynx]]) and digestive ([[esophagus]]) pathways. 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. Corresponding roughly to the area located between the 4th and 6th [[cervical vertebrae]], the superior boundary of the laryngopharynx is at the level of the [[hyoid bone]]. The laryngopharynx includes three major sites: the [[piriform sinus|pyriform sinus]], postcricoid area, and the posterior pharyngeal wall. Like the oropharynx above it, the laryngopharynx serves as a passageway for food and air and is lined with a [[stratified squamous epithelium]]. It is innervated by the [[pharyngeal plexus of vagus nerve|pharyngeal plexus]].

The vascular supply to the laryngopharynx includes the [[superior thyroid artery]], the [[lingual artery]] and the [[ascending pharyngeal artery]]. The primary neural supply is from both the [[vagus nerve|vagus]] and [[glossopharyngeal nerves|glossopharyngeal]] nerves. The vagus nerve provides a branch termed "Arnolds Nerve" which also supplies the external auditory canal, thus laryngopharyngeal cancer can result in referred otalgia. This nerve is also responsible for the ear-cough reflex in which stimulation of the ear canal results in a person coughing.

==Clinical significance==
===Inflammation===

''Pharyngitis'' is an inflammation of the throat or pharynx.<ref>Dorlands Dictionary, volume six, pharyngitis</ref> In most cases it is painful, and thus is often referred to as a ''sore throat''. Inflammation of the tonsils (tonsillitis) and/or larynx (laryngitis) may occur simultaneously, which can make eating difficult or painful. 

Most cases are caused by virus|viral infections (40%-60%), with the remainder caused by  bacterial infections,  fungus|fungal infections, or irritants such as pollutants or chemical substances.<ref>{{cite web |url=http://www.emedicine.com/emerg/TOPIC419.HTM |title=eMedicine - Pharyngitis : Article by John R Acerra }}</ref>

Treatment of viral causes are mainly symptomatic while bacterial or fungal causes may be amenable to antibiotics and antifungals respectively.

===Pharyngeal cancer===

Neck squamous cell carcinoma, an oropharyngeal cancer, occurs in humans.<ref name=Almadori>{{ cite journal |author=Almadori G, Bussu F, Galli J, Limongelli A, Persichilli S, Zappacosta B, Minucci A, Paludetti G, Giardina B |title=Salivary glutathione and uric acid levels in patients with head and neck squamous cell carcinoma
|journal=Head Neck.
|volume=29
|issue=7
|pages=648-54
|date=July 2007
|pmid=17274058 }}</ref>

==History==
===Etymology===
The word ''pharynx'' (pronounced {{IPAc-en|ˈ|f|ær|ɪ|ŋ|k|s}}<ref>''[[OED]]'' 2nd edition, 1989.</ref><ref>[http://www.merriam-webster.com/dictionary/pharynx Entry "pharynx"] in ''[http://www.merriam-webster.com/ Merriam-Webster Online Dictionary]'', retrieved 2012-07-28.</ref>) is derived from the [[Ancient Greek|Greek]] φάρυγξ ''phárynx'', meaning "throat". Its plural form is ''pharynges'' {{IPAc-en|f|ə|ˈ|r|ɪ|n|dʒ|i:|z}} or ''pharynxes'' {{IPAc-en|ˈ|f|ær|ɪ|ŋ|k|s|ə|z}}, and its adjective form is ''[[pharyngeal]]'' ({{IPAc-en|ˌ|f|æ|r|ɪ|n|ˈ|dʒ|iː|ə|l|}} <small>or</small> {{IPAc-en|f|ə|ˈ|r|ɪ|n|dʒ|i|ə|l}}).

==Other animals==
=== Vertebrates ===
All vertebrates have a pharynx, used in both feeding and respiration. The pharynx arises during development in all vertebrates through a series of six or more outpocketings on the lateral sides of the head. These outpocketings are [[pharyngeal arches]], and they give rise to a number of different structures in the skeletal, muscular and circulatory systems. The structure of the pharynx varies across the vertebrates. It differs in dogs, horses and ruminants. In dogs a single duct connects the nasopharynx to the nasal cavity. The tonsils are a compact mass which point away from the lumen of the pharynx.
In the horse the auditory tube opens into the guttural pouch and the tonsils are diffuse and raised slightly. Horses are unable to breathe through the mouth as the free apex of the rostral epiglottis lies dorsal to the soft palate in a normal horse. In [[ruminant]]s the tonsils are a compact mass which point towards the lumen of the pharynx.

Pharyngeal arches are characteristic features of vertebrates whose origin can be traced back through [[chordates]] to basal [[deuterostomes]] who also share endodermal outpocketings of the pharyngeal apparatus. Similar patterns of gene expression can be detected in the developing pharynx of [[amphioxus]] and [[hemichordates]]. However, the vertebrate pharynx is unique in that it gives rise to [[endoskeletal]] support through the contribution of [[neural crest]] cells.<ref name="pmid23020903">{{Cite journal
 | pmid = 23020903
| year = 2012
| author1 = Graham
| first1 = A
| title = Developmental and evolutionary origins of the pharyngeal apparatus
| journal = EvoDevo
| volume = 3
| issue = 3
| pages = 24
| last2 = Richardson
| first2 = J
| doi = 10.1186/2041-9139-3-24
| pmc = 3564725
}}</ref>

'''[[Pharyngeal jaws]]''' are a "second set" of [[jaw]]s contained within the pharynx of many species of  fish, distinct from the primary (oral) jaws. Pharyngeal jaws have been studied in [[moray eel]]s where their specific action is noted.  When the moray bites [[predation|prey]], it first bites normally with its oral jaws, capturing the prey. Immediately thereafter, the pharyngeal jaws are brought forward and bite down on the prey to grip it; they then retract, pulling the prey down the eel's [[esophagus]], allowing it to be swallowed.<ref name="Mehta2007">{{cite journal | last =Mehta | first =Rita S. | authorlink =Rita Mehta |author2=Peter C. Wainwright | title =Raptorial jaws in the throat help moray eels swallow large prey | journal =[[Nature (journal)|Nature]] | volume =449 | pages =79–82 | date =2007-09-06 | url =http://www.nature.com/nature/journal/v449/n7158/abs/nature06062.html | doi =10.1038/nature06062 | accessdate =2007-09-06 | pmid =17805293 | issue =7158}}</ref>

=== Invertebrates ===
[[Invertebrate]]s also have a pharynx.  Invertebrates with a pharynx include the [[tardigrade]]s,<ref>{{Cite journal | doi = 10.1046/j.1439-0469.2001.00140.x| title = Are the supportive structures of the tardigrade pharynx homologous throughout the entire group?| journal = Journal of Zoological Systematics and Evolutionary Research| volume = 39| pages = 1| year = 2001| last1 = Eibye-Jacobsen}}</ref>[[annelid]]s and [[arthropod]]s,<ref>{{Cite journal | doi = 10.1016/S0020-7322(98)00027-0| title = Microspines in the alimentary canal of arthropoda, onychophora, annelida| journal = International Journal of Insect Morphology and Embryology| volume = 27| issue = 4| pages = 341| year = 1998| last1 = Elzinga | first1 = R. J. }}</ref> and the [[priapulida|priapulids]] (which have an eversible pharynx).<ref>{{Cite journal | last1 = 
 Morse| first1 = 
 M. Patricia| last2 = | first2 =  | year = 
 1981| title = Meiopriapulus fijiensis n. gen., n. sp.: An Interstitial Priapulid from Coarse Sand in Fiji | journal = 
 Transactions of the American Microscopical Society| volume = 
 100| issue = 
 3| pages = 
 239| publisher =  | jstor = 3225549 | doi=10.2307/3225549 | url =  | format =  | accessdate = }}</ref>

The term "pharynx" is used loosely across the animal kingdom for the portion of the digestive tract loosely analogous to the vertebrate pharynx, but this need not imply deep structural or developmental similarities, or that the structures are [[homology (biology)|homologous]].{{citation needed|date=May 2014}}

The "pharynx" of the [[nematode worm]] is a muscular food pump in the head, triangular in cross-section, that grinds food and transports it directly to the intestines. A one-way valve connects the pharynx to the excretory canal.

{{clear}}

==Additional images==
<gallery>
 Image:Illu conducting passages.svg|Conducting passages
 Image:Illu dige tract.jpg|Organs of the digestive system
 Image:Illu nose nasal cavities.jpg|Nose and nasal
 Image:Gray907.png|[[Coronal section]] of right ear, showing [[Eustachian tube|auditory tube]] and  [[levator veli palatini]] muscle.
 Image:Gray955.png|The entrance to the larynx, viewed from behind
 Image:Gray1032.png|The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind.
 Image:Pharyngitis.jpg|Acute catarrhal [[pharyngitis]]. The oropharynx is swollen and red
File:Slide1kuku.JPG|Deep dissection of human larynx, pharynx and tongue seen from behind
File:Gray994.png|The '''nasopharynx''', '''oropharynx''', and '''laryngopharynx or larynx''' can be seen clearly in this [[Sagittal plane|sagittal]] section of the head and neck.
</gallery>

==See also==
{{Anatomy-terms}}
*[[Nasopharyngeal carcinoma]]
*[[Pharyngeal consonant]]
*[[Pharyngeal (disambiguation)]]
*[[Pharyngitis]]
*''[[Saccopharynx]]'', a genus of deep sea eel-like fishes with large mouths, distensible stomachs and long scaleless bodies
*[[Tonsil]]
*[[Uvula]]

==References==
{{Gray's}}
{{Reflist|2}}

'''General'''
* [https://web.archive.org/web/20081221120754/http://activate.lww.com/semdweb/internetsomd/ASP/1551471.asp Pharynx], Stedman's Online Medical Dictionary at Lippincott Williams and Wilkins
* ''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

==External links==
{{wiktionary}}
{{commons category}}
* {{SUNYAnatomyLabs|31|st|14|01}}
* {{SUNYAnatomyLabs|31|st|14|03}}
* {{SUNYAnatomyLabs|31|st|14|06}}

{{Human system and organs}}
{{Nose anatomy}}
{{Mouth anatomy}}
{{Digestive tract}}

{{Authority control}}
[[Category:Digestive system]]
[[Category:Human head and neck]]
[[Category:Human throat]]
[[Category:Human voice]]
[[Category:Respiratory system]]
[[Category:Animal anatomy]]

{{WikiDoc Help Menu}}
{{WikiDoc Sources}}