Pharynx

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Pharynx
Illu01 head neck.jpg
Head and neck
Illu pharynx.jpg
Pharynx
Latin(Greek: Pharynx)
Gray'ssubject #244 1141
Arterypharyngeal branches of ascending pharyngeal artery, ascending palatine, descending palatine, pharyngeal branches of inferior thyroid
Veinpharyngeal plexus
Nervepharyngeal plexus, maxillary nerve, mandibular nerve
MeSHPharynx
 
  (Redirected from Human pharynx)
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Pharynx
Illu01 head neck.jpg
Head and neck
Illu pharynx.jpg
Pharynx
Latin(Greek: Pharynx)
Gray'ssubject #244 1141
Arterypharyngeal branches of ascending pharyngeal artery, ascending palatine, descending palatine, pharyngeal branches of inferior thyroid
Veinpharyngeal plexus
Nervepharyngeal plexus, maxillary nerve, mandibular nerve
MeSHPharynx

The pharynx (plural: pharynges) is an organ found in animals, including humans. It is part of the digestive system and also the respiratory system. The pharynx is also part of the conducting zone of the respiratory system which is made up of the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles; their function is to filter, warm, and moisten air and conduct it into the lungs.[citation needed]

In humans it makes up the part of the throat situated immediately posterior to the nasal cavity, posterior to the mouth and superior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx (epipharynx), the oropharynx (mesopharynx), and the laryngopharynx (hypopharynx). The pharynx is part of the digestive system and also the respiratory system; it is also important in vocalization.

The word pharynx (pronounced /ˈfærɪŋks/[1][2]) is derived from the Greek phárynx, meaning "throat". Its plural form is pharynges /fəˈrɪnz/ or pharynxes /ˈfærɪŋksəz/, and its adjective form is pharyngeal (/ˌfærɪnˈəl/ or /fəˈrɪniəl/).

Divisions[edit]

Nasopharynx[edit]

The higher or most cephalad portion of the pharynx. It extends from the base of the skull to the upper surface of the soft palate.[3] It includes the space between the internal nares and the soft palate and lies above/superior to the oral cavity. The pharyngeal tonsils, more commonly referred to as the adenoids, are lymphoid tissue structures located in the posterior wall of the nasopharynx.

The nasopharynx, oropharynx, and laryngopharynx or larynx can be seen clearly in this sagittal section of the head and neck.

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 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:

Behind the ostium 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; it is known as the pharyngeal bursa.

Oropharynx[edit]

The oropharynx or mesopharynx 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 mouth, while in its lateral wall, between the Palatoglossal arch and the Palatopharyngeal arch, is the palatine tonsil. 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 air pass through the pharynx, a flap of connective tissue called the epiglottis closes over the glottis when food is swallowed to prevent aspiration.The oropharynx is lined by non keratinised squamous stratified epithelium.

The HACEK organisms (Haemophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella) 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.[4] Fusobacterium is a pathogen.[5]

Laryngopharynx[edit]

The hypopharynx or laryngopharynx or (Latin: pars laryngea pharyngis) is the 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 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.

The word pharynx (pronounced /ˈfærɪŋks/[6][7]) is derived from the Greek phárynx, meaning "throat". Its plural form is pharynges /fəˈrɪnz/ or pharynxes /ˈfærɪŋksəz/, and its adjective form is pharyngeal (/ˌfærɪnˈəl/ or /fəˈrɪniəl/).

Other animals[edit]

As in humans other animals also have pharynxes. It is part of the digestive system and also the respiratory system.

Pharyngeal jaws[edit]

Pharyngeal jaws are a "second set" of jaws contained within an animal's pharynx, distinct from the primary (oral) jaws. Pharyngeal jaws have been studied in moray eels. When the moray bites 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. [8]

An illustration of the pharyngeal jaws of a moray eel.

Additional images[edit]

See also[edit]

References[edit]

  1. ^ OED 2nd edition, 1989.
  2. ^ Entry "pharynx" in Merriam-Webster Online Dictionary, retrieved 2012-07-28.
  3. ^ Clinical Head and Neck and Functional Neuroscience Course Notes, 2008-2009, Uniformed Services University of the Health Sciences School of Medicine, Bethesda, Maryland
  4. ^ Morpeth S, Murdoch D, Cabell CH, et al. (December 2007). "Non-HACEK gram-negative bacillus endocarditis". Ann. Intern. Med. 147 (12): 829–35. PMID 18087053. 
  5. ^ Aliyu SH, Marriott RK, Curran MD, et al. (2004). "Real-time PCR investigation into the importance of Fusobacterium necrophorum as a cause of acute pharyngitis in general practice". J Med Microbiol 53 (Pt 10): 1029–35. doi:10.1099/jmm.0.45648-0. PMID 15358827. 
  6. ^ OED 2nd edition, 1989.
  7. ^ Entry "pharynx" in Merriam-Webster Online Dictionary, retrieved 2012-07-28.
  8. ^ Mehta, Rita S.; Peter C. Wainwright (2007-09-06). "Raptorial jaws in the throat help moray eels swallow large prey". Nature 449 (7158): 79–82. doi:10.1038/nature06062. PMID 17805293. Retrieved 2007-09-06. 
General

External links[edit]

This article incorporates text from a public domain edition of Gray's Anatomy.