Pharynx
Encyclopedia
The human pharynx is the part of the throat
situated immediately posterior to (under) the mouth
and nasal cavity
, and anterior 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
.
. It includes the space between the internal nares
and the soft palate and lies 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.
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.
to the level of the hyoid bone
. It opens anteriorly, through the isthmus faucium, into the mouth
, while in its lateral wall, between the two palatine arches
, 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. Fusobacterium
is a pathogen.
: 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
.
Throat
In vertebrate anatomy, the throat is the anterior part of the neck, in front of the vertebral column. It consists of the pharynx and larynx...
situated immediately posterior to (under) the mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
and nasal cavity
Nasal cavity
The nasal cavity is a large air filled space above and behind the nose in the middle of the face.- Function :The nasal cavity conditions the air to be received by the other areas of the respiratory tract...
, and anterior to the esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
and larynx
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
. The human pharynx is conventionally divided into three sections: the nasopharynx
Nasopharynx
The nasopharynx is the uppermost part of the pharynx. It extends from the base of the skull to the upper surface of the soft palate; it differs from the oral and laryngeal parts of the pharynx in that its cavity always remains patent .-Lateral:On its lateral wall is the pharyngeal ostium of the...
(epipharynx), the oropharynx
Oropharynx
The Oropharynx reaches 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 two palatine arches, is the palatine tonsil....
(mesopharynx), and the laryngopharynx (hypopharynx). The pharynx is part of the digestive system and also the respiratory system
Respiratory system
The respiratory system is the anatomical system of an organism that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles...
; it is also important in vocalization
Speech production
Speech production is the process by which spoken words are selected to be produced, have their phonetics formulated and then finally are articulated by the motor system in the vocal apparatus...
.
Nasopharynx
The nasopharynx is the most cephalad portion of the pharynx. It extends from the base of the skull to the upper surface of the soft palateSoft palate
The soft palate is the soft tissue constituting the back of the roof of the mouth. The soft palate is distinguished from the hard palate at the front of the mouth in that it does not contain bone....
. It includes the space between the internal nares
Choana
Choana is the posterior nasal aperture.The choanae are separated by the vomer.- Boundaries :It is the opening between the nasal cavity and the nasopharynx....
and the soft palate and lies 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 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
Torus tubarius
The base of the cartilaginous portion of the Eustachian tube lies directly under the mucous membrane of the nasal part of the pharynx, where it forms an elevation, the torus tubarius, the torus of the auditory tube, or cushion, behind the pharyngeal orifice of the tube...
or cushion, caused by the medial end of the cartilage of the tube that elevates the mucous membrane
Mucous membrane
The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...
. Two folds arise from the cartilaginous opening:
- the salpingopharyngeal foldSalpingopharyngeal foldA vertical fold of mucous membrane, the salpingopharyngeal fold, stretches from the lower part of the torus tubarius; it contains the Salpingopharyngeus muscle....
, a vertical fold of mucous membrane extending from the inferior part of the torus and containing the salpingopharyngeus muscleSalpingopharyngeus muscleThe salpingopharyngeus muscle arises from the inferior part of the cartilage of the pharyngotympanic tube in the nasal cavity; it passes downward and blends with the posterior fasciculus of the palatopharyngeus muscle.... - the salpingopalatine foldSalpingopalatine foldIn the lateral wall of the nasopharynx, the salpingopalatine fold, smaller than the salpingopharyngeal fold, stretches from the upper part of the torus tubarius to the palate anteroinferiorly; it contains the levator veli palatini muscle...
, a smaller fold extending from the superior part of the torus to the palate and containing the levator veli palatiniLevator veli palatiniThe levator veli palatini is the elevator muscle of the soft palate in the human body. During swallowing, it contracts, elevating the soft palate to help prevent food from entering the nasopharynx...
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 ostium of the auditory tube is a deep recess, the pharyngeal recess
Pharyngeal recess
Behind the ostium of the eustacian tube is a deep recess, the pharyngeal recess .-Clinical significance:At the base of this recess is the retropharyngeal lymph node This is clinically significant in that it may be involved in certain head and neck cancers, notably Nasopharyngeal cancer....
(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
Occipital bone
The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoidal in shape and curved on itself...
; it is known as the pharyngeal bursa.
Oropharynx
The oropharynx or mesopharynx lies behind the oral cavity, extending from the uvulaUvula
The palatine uvula, usually referred to as simply the uvula , is the conic projection from the posterior edge of the middle of the soft palate, composed of connective tissue containing a number of racemose glands, and some muscular fibers .-Function in language:The uvula plays a role in the...
to the level of the hyoid bone
Hyoid bone
The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...
. It opens anteriorly, through the isthmus faucium, into the mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
, while in its lateral wall, between the two palatine arches
Palatine arches
Palatine arches can refer to:* Palatoglossal arch* Palatopharyngeal arch...
, is the palatine tonsil. The anterior wall consists of the base of the tongue and the epiglottic vallecula
Epiglottic vallecula
The epiglottic vallecula is a depression just behind the root of the tongue between the folds in the throat. These depressions serve as "spit traps"; saliva is temporarily held in the valleculae to prevent initiation of the swallowing reflex....
; 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
Food
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...
and air
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
pass through the pharynx, a flap of connective tissue called the epiglottis
Epiglottis
The epiglottis is a flap that is made of elastic cartilage tissue covered with a mucous membrane, attached to the entrance of the larynx. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally. The term, like tonsils, is often incorrectly used to refer to the uvula...
closes over the glottis when food is swallowed to prevent aspiration
Pulmonary aspiration
Pulmonary aspiration is the entry of material from the oropharynx or gastrointestinal tract into the larynx and lower respiratory tract...
.The oropharynx is lined by non keratinised squamous stratified epithelium.
The HACEK organisms (Haemophilus
Haemophilus
Not to be confused with Haemophilia.Haemophilus is a genus of Gram-negative, pleomorphic, coccobacilli bacteria belonging to the Pasteurellaceae family. While Haemophilus bacteria are typically small coccobacilli, they are categorized as pleomorphic bacteria because of the wide range of shapes they...
, Actinobacillus actinomycetemcomitans
Actinobacillus
Actinobacillus is a genus of gram-negative, immotile and nonspore-forming, oval to rod-shaped bacteria occurring as parasites or pathogens in mammals, birds, and reptiles. It is a member of the Pasteurellaceae family. The bacteria are facultatively aerobic or anaerobic, capable of fermenting...
, Cardiobacterium hominis
Cardiobacterium hominis
Cardiobacterium hominis is a Gram-negative rod commonly grouped with other bacteria into the HACEK group. It is one of several bacteria normally present in the respiratory tract. However, it may also rarely cause endocarditis, an infection of the heart valves.-Microbiology:C. hominis is a...
, Eikenella corrodens
Eikenella
Eikenella corrodens is a fastidious gram-negative facultative anaerobic bacillus. It was first identified by M. Eiken in 1958, who called it Bacteroides corrodens.-Microbiology:...
, 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. Fusobacterium
Fusobacterium
Fusobacterium is a genus of filamentous, anaerobic, Gram-negative bacteria, similar to Bacteroides.Fusobacterium contribute to several human diseases, including periodontal diseases, Lemierre's syndrome, and topical skin ulcers...
is a pathogen.
Laryngopharynx
The laryngopharynx or hypopharynx (LatinLatin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
: 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
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
) pathways. At that point, the laryngopharynx is continuous with the esophagus posteriorly. The esophagus conducts food and fluids to the stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
; 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
Hyoid bone
The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...
. The laryngopharynx includes three major sites: the pyriform sinus
Piriform sinus
On either side of the laryngeal orifice is a recess, termed the piriform sinus , which is bounded medially by the aryepiglottic fold, laterally by the thyroid cartilage and hyothyroid membrane...
, 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
Stratified squamous epithelium
A stratified squamous epithelium consists of squamous epithelial cells arranged in layers upon a basement membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity...
. It is innervated by the pharyngeal plexus
Pharyngeal plexus of vagus nerve
The pharyngeal plexus is a network of nerve fibers innervating most of the palate, larynx, and pharynx.It is located on the surface of the middle pharyngeal constrictor muscle.-Sources:...
.
See also
- Pharyngeal consonantPharyngeal consonantA pharyngeal consonant is a type of consonant which is articulated with the root of the tongue against the pharynx.-Pharyngeal consonants in the IPA:Pharyngeal consonants in the International Phonetic Alphabet :...
- Nasopharyngeal carcinomaNasopharyngeal carcinomaNasopharyngeal carcinoma is the most common cancer originating in the nasopharynx, the uppermost region of the pharynx , behind the nose where the nasal passages and auditory tubes join the remainder of the upper respiratory tract. NPC differs significantly from other cancers of the head and neck...
- PharyngitisPharyngitisPharyngitis is an inflammation of the throat or pharynx. In most cases it is quite painful, and is the most common cause of a sore throat.Like many types of inflammation, pharyngitis can be acute – characterized by a rapid onset and typically a relatively short course – or chronic....
- TonsilTonsilPalatine tonsils, occasionally called the faucial tonsils, are the tonsils that can be seen on the left and right sides at the back of the throat....
- UvulaUvulaThe palatine uvula, usually referred to as simply the uvula , is the conic projection from the posterior edge of the middle of the soft palate, composed of connective tissue containing a number of racemose glands, and some muscular fibers .-Function in language:The uvula plays a role in the...
- The Man whose Pharynx was badThe Man whose Pharynx was bad"The Man whose Pharynx was bad" is a poem from Wallace Stevens's first book of poetry, Harmonium. It was first published in 1921, so it is in the public domain.One point of entry into this poem is Stevens's attitude towards the weather...
External links
- http://www.med.mun.ca/anatomyts/head/hnl2a.htm