Pharynx

The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the esophagus and larynx – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, though its structure varies across species.

In humans, the pharynx is part of the digestive system and the conducting zone of the respiratory system. (The conducting zone—which also includes the nostrils of the nose, the larynx, trachea, bronchi, and bronchioles—filters, warms and moistens air and conducts it into the lungs).[1] The human pharynx is conventionally divided into three sections: the nasopharynx, oropharynx, and laryngopharynx. It is also important in vocalization.

In humans, two sets of pharyngeal muscles form the pharynx and determine the shape of its lumen. They are arranged as an inner layer of longitudinal muscles and an outer circular layer.

Pharynx
Illu01 head neck
Head and inner neck
Illu pharynx
Pharynx
Details
Part ofThroat
SystemRespiratory system, digestive system
Arterypharyngeal branches of ascending pharyngeal artery, ascending palatine, descending palatine, pharyngeal branches of inferior thyroid
Veinpharyngeal plexus
Nervepharyngeal plexus, maxillary nerve, mandibular nerve
Identifiers
Latinpharynx
Greekφάρυγξ (phárynx)
MeSHD010614
TAA05.3.01.001
FMA46688
Anatomical terminology

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.[2] It includes the space between the 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. The nasopharynx is lined by respiratory epithelium that is pseudostratified, columnar, and ciliated.

Blausen 0872 UpperRespiratorySystem
Upper respiratory system, with nasopharynx, oropharynx and laryngopharynx labeled at right.

Polyps or mucus can obstruct the nasopharynx, as can congestion due to an upper respiratory infection. The auditory tube, which connect the middle ear to the pharynx, opens into the nasopharynx at the pharyngeal opening of the auditory tube. The opening and closing of the auditory tubes serves to equalize the barometric pressure in the middle ear with that of the ambient atmosphere.

Torus tubarius dissection
Details of torus tubarius

The anterior aspect of the nasopharynx communicates through the choanae with the nasal cavities. On its lateral wall is the pharyngeal opening 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 which 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, in front of the salpingopharyngeal fold, extending from the superior part of the torus to the palate and containing the levator veli palatini muscle. It also contains some muscle fibres called salpingopalatine muscle[3] The tensor veli palatini is lateral to the levator and does not contribute to the fold, since the origin is deep to the cartilaginous opening.

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 mouth, while in its lateral wall, between the palatoglossal arch and the palatopharyngeal arch, is the palatine tonsil.[4] 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.[5] Fusobacterium is a pathogen.[6]

Laryngopharynx

The laryngopharynx, (Latin: pars laryngea pharyngis), also known as hypopharynx, 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 (laryngeal) and digestive (oesophageal) 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 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 and 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

Pharyngitis
Pharyngitis is the painful swelling of the throat. The oropharynx shown here is very inflamed and red.

Inflammation

Inflammation of the pharynx, or pharyngitis, is the painful inflammation of the throat.

Pharyngeal cancer

Pharyngeal cancer is a cancer that originates in the neck and/or throat, and can cause serious clinical problems.

Waldeyer's tonsillar ring

Waldeyer's tonsillar ring is an anatomical term collectively describing the annular arrangement of lymphoid tissue in the pharynx. Waldeyer's ring circumscribes the naso- and oropharynx, with some of its tonsillar tissue located above and some below the soft palate (and to the back of the oral cavity). It is believed that Waldeyer's ring prevents the invasion of microorganisms from going into the air and food passages and this helps in the defense mechanism of the respiratory and alimentary systems.[7]

History

Etymology

The word pharynx (/ˈfærɪŋks/[8][9]) is derived from the Greek φάρυγξ phárynx, meaning "throat". Its plural form is pharynges /fəˈrɪndʒiːz/ or pharynxes /ˈfærɪŋksəz/, and its adjective form is pharyngeal (/ˌfærɪnˈdʒiːəl/ or /fəˈrɪndʒiəl/).

Other 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 ruminants the tonsils are a compact mass which point towards the lumen of the pharynx.

Pharyngeal arches

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.[10]

Pharyngeal jaws

Pharyngeal jaws of moray eels
An illustration of the pharyngeal jaws of a moray eel

Pharyngeal jaws are a "second set" of jaws contained within the pharynx of many species of fish, distinct from the primary (oral) jaws. Pharyngeal jaws have been studied in moray eels where their specific action is noted. 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.[11]

Invertebrates

Invertebrates also have a pharynx. Invertebrates with a pharynx include the tardigrades,[12] annelids and arthropods,[13] and the priapulids (which have an eversible pharynx).[14]

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.

Alitta virens pharynx (lateral)

Everted pharynx of Alitta virens (also known as Nereis virens), lateral view

Prorhynchus fontinalis pharynx

Pharynx of the flatworm Prorhynchus fontinalis

Peerj-297-fig-5 Platydemus manokwari

Pharynx of the flatworm Platydemus manokwari visible as the worm feeds on a snail.

C elegans anatomy

Longitudinal section through the roundworm Caenorhabditis elegans showing the position of the pharynx in the animal body.

Lamprey Larva x sect pharynx labelled

Microscopic cross section through the pharynx of a larva from an unknown lamprey species.

Additional images

Illu nose nasal cavities

Nose and nasal

Gray907

Coronal section of right ear, showing auditory tube and levator veli palatini muscle.

Gray955

The entrance to the larynx, viewed from behind

Slide1kuku

Deep dissection of human larynx, pharynx and tongue seen from behind

Gray994

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

See also

References

This article incorporates text in the public domain from page 1141 of the 20th edition of Gray's Anatomy (1918)

  1. ^ Respiratory Syster (PDF). Benjamin Cummings (Pearson Education, Inc). 2006. p. 1.
  2. ^ Clinical Head and Neck and Functional Neuroscience Course Notes, 2008-2009, Uniformed Services University of the Health Sciences School of Medicine, Bethesda, Maryland
  3. ^ Simkins, C. S. (1943). "Functional anatomy of the Eustachian tube". Archives of Otolaryngology–Head & Neck Surgery. 38 (5): 476–484. doi:10.1001/archotol.1943.00670040495009.
  4. ^ "The Pharynx". 28 July 2013.
  5. ^ Morpeth S, Murdoch D, Cabell CH, et al. (December 2007). "Non-HACEK gram-negative bacillus endocarditis". Ann. Intern. Med. 147 (12): 829–35. doi:10.7326/0003-4819-147-12-200712180-00002. PMID 18087053.
  6. ^ 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.
  7. ^ "Pharynx".
  8. ^ OED 2nd edition, 1989.
  9. ^ Entry "pharynx" in Merriam-Webster Online Dictionary, retrieved 2012-07-28.
  10. ^ Graham, A; Richardson, J (2012). "Developmental and evolutionary origins of the pharyngeal apparatus". EvoDevo. 3 (3): 24. doi:10.1186/2041-9139-3-24. PMC 3564725. PMID 23020903.
  11. ^ Mehta, Rita S.; Wainwright, Peter C. (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.
  12. ^ Eibye-Jacobsen (2001). "Are the supportive structures of the tardigrade pharynx homologous throughout the entire group?". Journal of Zoological Systematics and Evolutionary Research. 39: 1. doi:10.1046/j.1439-0469.2001.00140.x.
  13. ^ Elzinga, R.J. (1998). "Microspines in the alimentary canal of arthropoda, onychophora, annelida". International Journal of Insect Morphology and Embryology. 27 (4): 341. doi:10.1016/S0020-7322(98)00027-0.
  14. ^ Morse, M. Patricia (1981). "Meiopriapulus fijiensis n. gen., n. sp.: An Interstitial Priapulid from coarse sand in Fiji". Transactions of the American Microscopical Society. 100 (3): 239. doi:10.2307/3225549. JSTOR 3225549.

General

  • 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

Adenoid

The adenoid, also known as a pharyngeal tonsil or nasopharyngeal tonsil, is the superior-most of the tonsils. It is a mass of lymphatic tissue located behind the nasal cavity, in the roof of the nasopharynx, where the nose blends into the throat. In children, it normally forms a soft mound in the roof and back wall of the nasopharynx, just above and behind the uvula.

The term adenoid is also used to represent adenoid hypertrophy.

Ascending pharyngeal artery

The ascending pharyngeal artery is an artery in the neck that supplies the pharynx, developing from the proximal part of the embryonic second aortic arch.

It is the smallest branch of the external carotid and is a long, slender vessel, deeply seated in the neck, beneath the other branches of the external carotid and under the stylopharyngeus muscle. It lies just superior to the bifurcation of the common carotid arteries.

The artery most typically bifurcates into embryologically distinct pharyngeal and neuromeningeal trunks. The pharyngeal trunk usually consists of several branches which supply the middle and inferior pharyngeal constrictor muscles and the stylopharyngeus, ramifying in their substance and in the mucous membranes lining them. These branches are in hemodynamic equilibrium with contributors from the internal maxillary artery. The neuromeningeal trunk classically consists of jugular and hypoglossal divisions, which enter the jugular and hypoglossal foramina to supply regional meningeal and neural structures, being in equilibrium with branches of the vertebral, occipital, posterior meningeal, middle meningeal, and internal carotid arteries (via its caroticotympanic branch, meningohypophyseal, and inferolateral trunks). Also present is the inferior tympanic branch, which ascends towards the middle ear cavity; it is involved in internal carotid artery reconstitution via the "aberrant carotid artery" variant. The muscular branch of the ascending pharyngeal artery is in equilibrium with the odontoid arcade from the vertebral artery.

Ascidiacea

Ascidiacea (commonly known as the ascidians or sea squirts) is a paraphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer "tunic" made of the polysaccharide cellulose.

Ascidians are found all over the world, usually in shallow water with salinities over 2.5%. While members of the Thaliacea and Larvacea (Appendicularia) swim freely like plankton, sea squirts are sessile animals after their larval phase: they then remain firmly attached to their substratum, such as rocks and shells.

There are 2,300 species of ascidians and three main types: solitary ascidians, social ascidians that form clumped communities by attaching at their bases, and compound ascidians that consist of many small individuals (each individual is called a zooid) forming colonies up to several meters in diameter.

Sea squirts feed by taking in water through a tube, the oral siphon. The water enters the mouth and pharynx, flows through mucus-covered gill slits (also called pharyngeal stigmata) into a water chamber called the atrium, then exits through the atrial siphon.

Buccopharyngeal fascia

The buccopharyngeal fascia is a fascia in the head.

Parallel to the carotid sheath and along its medial aspect the pretracheal fascia gives off a thin lamina, the buccopharyngeal fascia, which closely invests the constrictor muscles of the pharynx and is continued forward from the constrictor pharyngis superior onto the buccinator.

It is attached to the prevertebral layer by loose connective tissue only, and thus an easily distended space, the retropharyngeal space, is found between them.

Glossopharyngeal nerve

The glossopharyngeal nerve, known as the ninth cranial nerve (CN IX), is a mixed nerve that carries afferent sensory and efferent motor information. It exits the brainstem out from the sides of the upper medulla, just rostral (closer to the nose) to the vagus nerve. The motor division of the glossopharyngeal nerve is derived from the basal plate of the embryonic medulla oblongata, while the sensory division originates from the cranial neural crest.

Human digestive system

The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has many stages. The first stage is the cephalic phase of digestion which begins with gastric secretions in response to the sight and smell of food. The next stage starts in the mouth.

Chewing, in which food is mixed with saliva, begins the mechanical process of digestion. This produces a bolus which can be swallowed down the esophagus to enter the stomach. Here it is mixed with gastric acid until it passes into the duodenum where it is mixed with a number of enzymes produced by the pancreas. Saliva also contains a catalytic enzyme called amylase which starts to act on food in the mouth. Another digestive enzyme called lingual lipase is secreted by some of the lingual papillae on the tongue and also from serous glands in the main salivary glands. Digestion is helped by the chewing of food carried out by the muscles of mastication, by the teeth, and also by the contractions of peristalsis, and segmentation. Gastric acid, and the production of mucus in the stomach, are essential for the continuation of digestion.

Peristalsis is the rhythmic contraction of muscles that begins in the esophagus and continues along the wall of the stomach and the rest of the gastrointestinal tract. This initially results in the production of chyme which when fully broken down in the small intestine is absorbed as chyle into the lymphatic system. Most of the digestion of food takes place in the small intestine. Water and some minerals are reabsorbed back into the blood in the colon of the large intestine. The waste products of digestion (feces) are defecated from the anus via the rectum.

Inferior pharyngeal constrictor muscle

The Inferior pharyngeal constrictor, the thickest of the three constrictors, arises from the sides of the cricoid and thyroid cartilage. Similarly to the superior and middle pharyngeal constrictor muscles, it is innervated by the vagus nerve (cranial nerve X), specifically, by branches from the pharyngeal plexus and by neuronal branches from the recurrent laryngeal nerve.

Pharyngeal consonant

A pharyngeal consonant is a consonant that is articulated primarily in the pharynx. Some phoneticians distinguish upper pharyngeal consonants, or "high" pharyngeals, pronounced by retracting the root of the tongue in the mid to upper pharynx, from (ary)epiglottal consonants, or "low" pharyngeals, which are articulated with the aryepiglottic folds against the epiglottis in the lower larynx, as well as from epiglotto-pharyngeal consonants, with both movements being combined.

Stops and trills can be reliably produced only at the epiglottis, and fricatives can be reliably produced only in the upper pharynx. When they are treated as distinct places of articulation, the term radical consonant may be used as a cover term, or the term guttural consonants may be used instead.

In many languages, pharyngeal consonants trigger advancement of neighboring vowels. Pharyngeals thus differ from uvulars, which nearly always trigger retraction. For example, in some dialects of Arabic, the vowel /a/ is fronted to [æ] next to pharyngeals, but it is retracted to [ɑ] next to uvulars, as in حال [ħæːl] 'condition', with a pharyngeal fricative and a fronted vowel, compared to خال [χɑːl] 'maternal uncle', with a uvular consonant and a retracted vowel.

In addition, consonants and vowels may be secondarily pharyngealized. Also, strident vowels are defined by an accompanying epiglottal trill.

Pharyngeal jaw

Pharyngeal jaws are a "second set" of jaws contained within an animal's throat, or pharynx, distinct from the primary or oral jaws. They are believed to have originated as modified gill arches, in much the same way as oral jaws.

Pharyngeal muscles

The pharyngeal muscles are a group of muscles that form the pharynx, which is posterior to the oral cavity, determining the shape of its lumen, and affecting its sound properties as the primary resonating cavity.

The pharyngeal muscles contract pushing the food into the esophagus. There are two muscular layers of the pharynx: the outer circular layer and the inner longitudinal layer.

The outer circular layer includes:

Inferior constrictor muscle

Middle constrictor muscle

Superior constrictor muscleDuring swallowing, these muscles constrict to propel bolus downwards (an involuntary process).

The inner longitudinal layer includes:

Stylopharyngeus muscle

Salpingopharyngeus muscle

Palatopharyngeus muscleDuring swallowing, these muscles act to shorten and widen the pharynx.

They are innervated by the pharyngeal branch of the Vagus nerve (CN X) with the exception of the stylopharyngeus muscle which is innervated by the glossopharyngeal nerve (CN IX).

Pharyngeal plexus of vagus nerve

The pharyngeal plexus is a network of nerve fibers innervating most of the palate and pharynx. (Larynx, which is innervated by superior and recurrent laryngeal nerve from vagus nerve (CN X), is not included)

It is located on the surface of the middle pharyngeal constrictor muscle.

Pharyngeal reflex

The pharyngeal reflex, gag reflex, or laryngeal spasm, is a reflex contraction of the back of the throat, evoked by touching the roof of the mouth, the back of the tongue, the area around the tonsils, the uvula, and the back of the throat. It, along with other aerodigestive reflexes such as reflexive pharyngeal swallowing, prevents objects in the oral cavity from entering the throat except as part of normal swallowing and helps prevent choking.

Pharyngeal slit

Pharyngeal slits are filter-feeding organs found in vertebrate chordates. Pharyngeal slits are repeated openings that appear along the pharynx caudal to the mouth. With this position, they allow for the movement of water in the mouth and out the pharyngeal slits. It is postulated that this is how pharyngeal slits first assisted in filter-feeding, and later with the addition of gills along their walls, aided in respiration of aquatic chordates. These repeated segments are controlled by similar developmental mechanisms. Some hemichordate species can have as many as 200 gill slits. Pharyngeal slits resembling gill slits are transiently present during the embryonic stages of tetrapod development. The presence of gill-like slits in the neck of the developing human embryo famously led Ernst Haeckel to postulate that "ontogeny recapitulates phylogeny"; this hypothesis, while false, contains elements of truth, as explored by Stephen Jay Gould in Ontogeny and Phylogeny. However, it is now accepted that it is the vertebrate pharyngeal pouches and not the neck slits that are homologous to the pharyngeal slits of invertebrate chordates. Gill slits are, at some stage of life, found in all chordates. One theory of their origin is the fusion of nephridia which opened both on the outside and the gut, creating openings between the gut and the environment.

Pharyngitis

Pharyngitis is inflammation of the back of the throat, known as the pharynx. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and a hoarse voice. Symptoms usually last 3–5 days. Complications can include sinusitis and acute otitis media. Pharyngitis is a type of upper respiratory tract infection.Most cases are caused by a viral infection. Strep throat, a bacterial infection, is the cause in about 25% of children and 10% of adults. Uncommon causes include other bacteria such as gonorrhea, fungus, irritants such as smoke, allergies, and gastroesophageal reflux disease. Specific testing is not recommended in people who have clear symptoms of a viral infection, such as a cold. Otherwise, a rapid antigen detection test (RADT) or throat swab is recommended. Other conditions that can produce similar symptoms include epiglottitis, thyroiditis, retropharyngeal abscess, and occasionally heart disease.NSAIDs, such as ibuprofen, can be used to help with the pain. Numbing medication, such as topical lidocaine, may also help. Strep throat is typically treated with antibiotics, such as either penicillin or amoxicillin. If steroids are useful in acute pharyngitis, other than possibly in severe cases, is unclear.About 7.5% of people have a sore throat in any 3-month period. Two or three episodes in a year are not uncommon. This resulted in 15 million physician visits in the United States in 2007. Pharyngitis is the most common cause of a sore throat. The word comes from the Greek word pharynx meaning "throat" and the suffix -itis meaning "inflammation".

Stertor

A stertor is a respiratory sound characterized by heavy snoring or gasping. It is caused by partial obstruction of airway above the level of the larynx and by vibrations of tissue of the naso-pharynx, pharynx or soft palate (this distinguishes it from stridor, which is caused by turbulent air flow below or in the larynx). It is low-pitched, non-musical, and occurs during the inspiratory phase only. In general terms it is a snoring or snuffly sound. Stertorous breathing will be audible during the post-ictal phase after a tonic-clonic seizure.

Stylopharyngeus muscle

The stylopharyngeus is a muscle in the head that stretches between the temporal styloid process and the pharynx.

Superior pharyngeal constrictor muscle

The superior pharyngeal constrictor muscle is a muscle in the pharynx. It is the highest located muscle of the three pharyngeal constrictors. The muscle is a quadrilateral muscle, thinner and paler than the inferior pharyngeal constrictor muscle and middle pharyngeal constrictor muscle.

The muscle is divided into four parts: A pterygopharyngeal, buccopharyngeal, mylopharyngeal and a glossopharyngeal part.

Swallowing

Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth, to the pharynx, and into the esophagus, while shutting the epiglottis. Swallowing is an important part of eating and drinking. If the process fails and the material (such as food, drink, or medicine) goes through the trachea, then choking or pulmonary aspiration can occur. In the human body the automatic temporary closing of the epiglottis is controlled by the swallowing reflex.

The portion of food, drink, or other material that will move through the neck in one swallow is called a bolus.

Swallowing comes so easily to most people that the process rarely prompts much thought. However, from the viewpoints of physiology, of speech-language pathology, and of health care for people with difficulty in swallowing (dysphagia), it is an interesting topic with extensive scientific literature.

Throat

In vertebrate anatomy, the throat is the front part of the neck, positioned in front of the vertebra. It contains the pharynx and larynx. An important section of it is the epiglottis, which is a flap, separating the trachea (windpipe) from esophagus, preventing food and drink being inhaled into the lungs. The throat contains various blood vessels, pharyngeal muscles, the nasopharyngeal tonsil, the tonsils, the palatine uvula, the trachea, the esophagus, and the vocal cords. Mammal throats consist of two bones, the hyoid bone and the clavicle. The "throat" is sometimes thought to be synonymous for the isthmus of the fauces.It works with the mouth, ears and nose, as well as a number of other parts of the body. Its pharynx is connected to the mouth, allowing speech to occur, and food and liquid to pass down the throat. It is joined to the nose by the nasopharynx at the top of the throat, and to ear by its Eustachian tube. The throat's trachea carries inhaled air to the bronchi of the lungs. The esophagus carries food through the throat to the stomach. Adenoids and tonsils help prevent infection and are composed of lymph tissue. The larynx contains vocal cords, the epiglottis (preventing food/liquid inhalation), and an area known as the subglottic larynx—the narrowest section of the upper part of the throat. In the larynx, the vocal cords consist of two membranes that act according to the pressure of the air.

Musculoskeletal
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Immune system
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