Esophagus

This is a good article. Click here for more information.
Source: Wikipedia, the free encyclopedia.
"Gullet" redirects here. For other uses, see Gullet (disambiguation).

Esophagus
vagus
Identifiers
Latinoesophagus
MeSHD004947
TA98A05.4.01.001
TA22887
FMA7131
Anatomical terminology]
Major parts of the
Gastrointestinal tract
Upper gastrointestinal tract
Lower gastrointestinal tract
See also
Salivary glandsParotid glandSubmandibular glandSublingual glandpharynxTongueEsophagusPancreasStomachPancreatic ductIleumAnusRectumVermiform appendixCecumDescending colonAscending colonTransverse colonColon (anatomy)Bile ductDuodenumGallbladderLiveroral cavity
Upper and lower human gastrointestinal tract

The esophagus (

heart, passes through the diaphragm, and empties into the uppermost region of the stomach. During swallowing, the epiglottis tilts backwards to prevent food from going down the larynx
and lungs. The word oesophagus is from Ancient Greek οἰσοφάγος (oisophágos), from οἴσω (oísō), future form of φέρω (phérō, "I carry") + ἔφαγον (éphagon, "I ate").

The wall of the esophagus from the

lower motor neurons
) which are carried in the vagus nerve to innervate its striated muscle.

The esophagus passes through the thoracic cavity into the diaphragm into the stomach.

The esophagus may be affected by

barium sulfate, endoscopy, and CT scans
. Surgically, the esophagus is difficult to access in part due to its position between critical organs and directly between the sternum and spinal column.[2]

Structure

The esophagus is one of the upper parts of the

eleventh thoracic vertebra.[4] The esophagus is usually about 25 cm (10 in) in length.[5]

Many

deep cervical lymph nodes, the middle into the superior and posterior mediastinal lymph nodes, and the lower esophagus into the gastric and celiac lymph nodes. This is similar to the lymphatic drainage of the abdominal structures that arise from the foregut, which all drain into the celiac nodes.[6]

Position
heart.
Diagram of thorax showing the esophagus and surrounding structures.
The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind.

The upper esophagus lies at the back of the mediastinum behind the

left atrium. At this point, it passes through the diaphragm.[4]

The

intercostal veins on the right side. The vagus nerve divides and covers the esophagus in a plexus.[4]

Constrictions
Diagram showing the four constrictions of the esophagus.
The esophagus is constricted in three places.[inconsistent]

The esophagus has four points of constriction. When a corrosive substance, or a solid object is swallowed, it is most likely to lodge and damage one of these four points. These constrictions arise from particular structures that compress the esophagus. These constrictions are:[8]

Sphincters

The esophagus is surrounded at the top and bottom by two muscular rings, known respectively as the upper esophageal sphincter and the lower esophageal sphincter.[4] These sphincters act to close the esophagus when food is not being swallowed. The upper esophageal sphincter is an anatomical sphincter, which is formed by the lower portion of the inferior pharyngeal constrictor, also known as the cricopharyngeal sphincter due to its relation with cricoid cartilage of the larynx anteriorly. However, the lower esophageal sphincter is not an anatomical but rather a functional sphincter, meaning that it acts as a sphincter but does not have a distinct thickening like other sphincters.

The upper esophageal sphincter surrounds the upper part of the esophagus. It consists of

inferior pharyngeal constrictor.[9]

The lower esophageal sphincter, or gastroesophageal sphincter, surrounds the lower part of the esophagus at the junction between the esophagus and the stomach.

cardia. Dysfunction of the gastroesophageal sphincter causes gastroesophageal reflux, which causes heartburn, and, if it happens often enough, can lead to gastroesophageal reflux disease, with damage of the esophageal mucosa.[11]

Nerve supply

The esophagus is innervated by the vagus nerve and the cervical and thoracic

sympathetic function. It may enhance the function of the vagus nerve, increasing peristalsis and glandular activity, and causing sphincter contraction. In addition, sympathetic activation may relax the muscle wall and cause blood vessel constriction.[6] Sensation along the esophagus is supplied by both nerves, with gross sensation being passed in the vagus nerve and pain passed up the sympathetic trunk.[4]

Gastroesophageal junction

The gastroesophageal junction (also known as the esophagogastric junction) is the junction between the esophagus and the stomach, at the lower end of the esophagus.[13] The pink color of the esophageal mucosa contrasts to the deeper red of the gastric mucosa,[6][14] and the mucosal transition can be seen as an irregular zig-zag line, which is often called the z-line.[15] Histological examination reveals abrupt transition between the stratified squamous epithelium of the esophagus and the simple columnar epithelium of the stomach.[16] Normally, the cardia of the stomach is immediately distal to the z-line[17] and the z-line coincides with the upper limit of the gastric folds of the cardia; however, when the anatomy of the mucosa is distorted in Barrett's esophagus the true gastroesophageal junction can be identified by the upper limit of the gastric folds rather than the mucosal transition.[18] The functional location of the lower oesophageal sphincter is generally situated about 3 cm (1+1⁄4 in) below the z-line.[6]

Microanatomy

Main article: Gastrointestinal wall
squamous cell epithelium of the esophageal wall
Histological section showing the gastroesophageal junction, with a black arrow pointing to the junction.
Histological
section of the gastroesophageal junction, with a black arrow indicating the junction
This article is one of a series on the
Gastrointestinal wall
General structure
Specific
  • Meissner's plexus
  • Auerbach's plexus
Organs

The human esophagus has a

cardiac glands of the stomach, located in the lamina propria and most frequent in the terminal part of the organ.[19][20] The mucus from the glands gives a good protection to the lining.[21] The submucosa also contains the submucosal plexus, a network of nerve cells that is part of the enteric nervous system.[19]

The

serosa. This makes it distinct from many other structures in the gastrointestinal tract that only have a serosa.[6]

Development

In early

embryogenesis, the esophagus develops from the endodermal primitive gut tube. The ventral part of the embryo abuts the yolk sac. During the second week of embryological development, as the embryo grows, it begins to surround parts of the sac. The enveloped portions form the basis for the adult gastrointestinal tract.[22] The sac is surrounded by a network of vitelline arteries. Over time, these arteries consolidate into the three main arteries that supply the developing gastrointestinal tract: the celiac artery, superior mesenteric artery, and inferior mesenteric artery. The areas supplied by these arteries are used to define the midgut, hindgut and foregut.[22]

The surrounded sac becomes the primitive gut. Sections of this gut begin to differentiate into the organs of the gastrointestinal tract, such as the esophagus,

intestines.[22] The esophagus develops as part of the foregut tube.[22] The innervation of the esophagus develops from the pharyngeal arches.[4]

Function

Swallowing

Food is

gastrointestinal tract. After food passes through the esophagus, it enters the stomach.[10] When food is being swallowed, the epiglottis moves backward to cover the larynx, preventing food from entering the trachea. At the same time, the upper esophageal sphincter relaxes, allowing a bolus of food to enter. Peristaltic contractions of the esophageal muscle push the food down the esophagus. These rhythmic contractions occur both as a reflex response to food that is in the mouth, and also as a response to the sensation of food within the esophagus itself. Along with peristalsis, the lower esophageal sphincter relaxes.[10]

Reducing gastric reflux

The stomach produces

crura of the diaphragm also help this sphincteric action.[10][23]

Gene and protein expression

About 20,000 protein-coding genes are expressed in human cells and nearly 70% of these genes are expressed in the normal esophagus.[24][25] Some 250 of these genes are more specifically expressed in the esophagus with less than 50 genes being highly specific. The corresponding esophagus-specific proteins are mainly involved in squamous differentiation such as keratins KRT13, KRT4 and KRT6C. Other specific proteins that help lubricate the inner surface of esophagus are mucins such as MUC21 and MUC22. Many genes with elevated expression are also shared with skin and other organs that are composed of squamous epithelia.[26]

Clinical significance

The main conditions affecting the esophagus are described here. For a more complete list, see esophageal disease.

Inflammation

Main article: Esophagitis

Inflammation of the esophagus is known as

eczema, and allergic rhinitis, though it is not clear whether these conditions contribute to eosinophilic esophagitis or vice versa, or if they are symptoms of mutual underlying factors.[27] Esophagitis can cause painful swallowing and is usually treated by managing the cause of the esophagitis - such as managing reflux or treating infection.[5]

Barrett's esophagus

Main article: Barrett's esophagus

Prolonged esophagitis, particularly from gastric reflux, is one factor thought to play a role in the development of

simple columnar epithelia. Barrett's esophagus is thought to be one of the main contributors to the development of esophageal cancer.[5]

Cancer

Main article: Esophageal cancer

There are two main types of

developed countries in those with Barrett's esophagus, and occurs in the cuboidal cells.[5]

In its early stages, esophageal cancer may not have any symptoms at all. When severe, esophageal cancer may eventually cause obstruction of the esophagus, making swallowing of any solid foods very difficult and causing weight loss. The progress of the cancer is

palliative therapy may also be a focus of treatment.[5]

Varices

Main article: Esophageal varices

anastomose (join up) with those of the portal vein when portal hypertension develops.[28] These blood vessels are engorged more than normal, and in the worst cases may partially obstruct the esophagus. These blood vessels develop as part of a collateral circulation that occurs to drain blood from the abdomen as a result of portal hypertension, usually as a result of liver diseases such as cirrhosis.[5]: 941–42  This collateral circulation occurs because the lower part of the esophagus drains into the left gastric vein, which is a branch of the portal vein. Because of the extensive venous plexus that exists between this vein and other veins, if portal hypertension occurs, the direction of blood drainage in this vein may reverse, with blood draining from the portal venous system, through the plexus. Veins in the plexus may engorge and lead to varices.[6][7]

Esophageal varices often do not have symptoms until they rupture. A ruptured varix is considered a medical emergency because varices can bleed a lot. A bleeding varix may cause a person

IV fluids and blood products may be given in order to prevent hypovolemia from excess blood loss.[5]

Motility disorders

Several disorders affect the motility of food as it travels down the esophagus. This can cause difficult swallowing, called

systemic sclerosis or in CREST syndrome may cause hardening of the walls of the esophagus and interfere with peristalsis.[5]

Malformations

Plummer-Vinson syndrome.[5]

Two of the most common

congenital malformations affecting the esophagus are an esophageal atresia where the esophagus ends in a blind sac instead of connecting to the stomach; and an esophageal fistula – an abnormal connection between the esophagus and the trachea.[30] Both of these conditions usually occur together.[30] These are found in about 1 in 3500 births.[31] Half of these cases may be part of a syndrome where other abnormalities are also present, particularly of the heart or limbs. The other cases occur singly.[32]

Imaging

A mass seen during an endoscopy and an ultrasound of the mass conducted during the endoscopy session.

An

swallowed barium may be used to reveal the size and shape of the esophagus, and the presence of any masses. The esophagus may also be imaged using a flexible camera inserted into the esophagus, in a procedure called an endoscopy. If an endoscopy is used on the stomach, the camera will also have to pass through the esophagus. During an endoscopy, a biopsy may be taken. If cancer of the esophagus is being investigated, other methods, including a CT scan, may also be used.[5]

History

The word esophagus (

naturalist Pliny the Elder (AD23–AD79),[35] and the peristaltic contractions of the esophagus have been documented since at least the time of Galen.[36]

The first attempt at surgery on the esophagus focused in the neck, and was conducted in dogs by

Theodore Billroth in 1871. In 1877 Czerny carried out surgery in people. By 1908, an operation had been performed by Voeckler to remove the esophagus, and in 1933 the first surgical removal of parts of the lower esophagus, (to control esophageal cancer), had been conducted.[37]

The

reflux, was first conducted by Rudolph Nissen in 1955.[37]

Other animals

Vertebrates

1: esophagus2: trachea3:tracheal lungs4: rudimentary left lung4: right lung6: heart7: liver8 stomach9: air sac10: gallbladder11: pancreas12: spleen13: intestine14: testicles15: kidneys
Anatomy of a snake.file info
  1. esophagus
  2. trachea
  3. tracheal lungs
  4. rudimentary left lung
  5. right lung
  6. heart
  7. liver
  8. stomach
  9. air sac
  10. gallbladder
  11. pancreas
  12. spleen
  13. intestine
  14. testicles
  15. kidneys
Accessory pancreatic duct, 17. Pancreatic duct.
18. Small intestine: 19. Duodenum, 20. Jejunum
21–22. Right and left kidneys.
The front border of the liver has been lifted up (brown arrow).[38]

In tetrapods, the pharynx is much shorter, and the esophagus correspondingly longer, than in fish. In the majority of vertebrates, the esophagus is simply a connecting tube, but in some birds, which regurgitate components to feed their young, it is extended towards the lower end to form a crop for storing food before it enters the true stomach.[39][40] In ruminants, animals with four stomachs, a groove called the sulcus reticuli is often found in the esophagus, allowing milk to drain directly into the hind stomach, the abomasum.[41] In the horse the esophagus is about 1.2 to 1.5 m (4 to 5 ft) in length, and carries food to the stomach. A muscular ring, called the cardiac sphincter, connects the stomach to the esophagus. This sphincter is very well developed in horses. This and the oblique angle at which the esophagus connects to the stomach explains why horses cannot vomit.[42] The esophagus is also the area of the digestive tract where horses may have the condition known as choke.

The esophagus of snakes is remarkable for the distension it undergoes when swallowing prey.[43]

In most fish, the esophagus is extremely short, primarily due to the length of the pharynx (which is associated with the

intestine, and is therefore somewhat longer.[39]

In many vertebrates, the esophagus is lined by

pepsinogen or hydrochloric acid have been found.[40]

The muscle of the esophagus in many mammals is initially striated but then becomes smooth muscle in the caudal third or so. In canines and ruminants, however, it is entirely striated to allow regurgitation to feed young (canines) or regurgitation to chew cud (ruminants). It is entirely smooth muscle in amphibians, reptiles and birds.[40]

Contrary to popular belief,[44] an adult human body would not be able to pass through the esophagus of a whale, which generally measures less than 10 cm (4 in) in diameter, although in larger baleen whales it may be up to 25 cm (10 in) when fully distended.[45]

Invertebrates

A structure with the same name is often found in invertebrates, including

molluscs and arthropods, connecting the oral cavity with the stomach.[46] In terms of the digestive system of snails and slugs, the mouth opens into an esophagus, which connects to the stomach. Because of torsion, which is the rotation of the main body of the animal during larval development, the esophagus usually passes around the stomach, and opens into its back, furthest from the mouth. In species that have undergone de-torsion, however, the esophagus may open into the anterior of the stomach, which is the reverse of the usual gastropod arrangement.[47] There is an extensive rostrum at the front of the esophagus in all carnivorous snails and slugs.[48] In the freshwater snail species Tarebia granifera, the brood pouch is above the esophagus.[49]

In the cephalopods, the brain often surrounds the esophagus.[50]

See also

This article uses anatomical terminology.

References

  1. ISBN 978-1-4058-8118-0
    .
  2. ^ Jacobo, Julia (24 November 2016). "Thanksgiving Tales From the Emergency Room". ABC News.
  3. ISBN 978-0-87893-695-3
    .
  4. ^
    ISBN 978-0-8089-2306-0
    .
  5. ^
    ISBN 978-0-7020-3084-0
    .
  6. ^
    doi:10.1038/gimo6 (inactive 31 January 2024).{{cite journal}}: CS1 maint: DOI inactive as of January 2024 (link
    )
  7. ^
    PMID 9347826
    .
  8. ISBN 978-0-443-06952-9
    .
  9. PMID 17074861
    .
  10. ^
    ISBN 978-0-7216-0240-0.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  11. PMID 18923172
    .
  12. doi:10.1038/gimo13 (inactive 31 January 2024). Retrieved 24 May 2014.{{cite journal}}: CS1 maint: DOI inactive as of January 2024 (link
    )
  13. ISBN 978-0-683-23125-0
    .
  14. ISBN 978-1-55642-511-0
    .
  15. ISBN 978-1-4557-1144-4
    .
  16. ISBN 978-0-7817-2830-0
    .
  17. ISBN 978-0-07-177401-7
    .
  18. ISBN 978-0-7234-3252-4
    .
  19. ^
    ISBN 978-0-7817-7200-6
    .
  20. ISBN 978-4-431-68616-3
    .
  21. ISBN 978-0-443-06850-8
    .
  22. ^
    ISBN 978-0-443-06811-9
    .
  23. ^ "Neuromuscular Anatomy of Esophagus and Lower Esophageal Sphincter - Motor Function of the Pharynx, Esophagus, and its Sphincters - NCBI Bookshelf". Ncbi.nlm.nih.gov. 25 March 2013. Retrieved 24 April 2013.
  24. ^ "The human proteome in esophagus - The Human Protein Atlas". www.proteinatlas.org. Retrieved 22 September 2017.
  25. S2CID 802377
    .
  26. PMID 25411189
    .
  27. S2CID 220976044
    .
  28. ISBN 978-1-4160-6257-8
    .
  29. ISBN 978-0-87893-695-3
    .
  30. ^
    ISBN 978-0-443-06583-5
    .
  31. PMID 16299066
    .
  32. S2CID 43782279
    .
  33. ^ Harper, Douglas. "Esophagus". Etymology Online. Retrieved 19 March 2014.
  34. ISBN 978-0-674-99640-3
    .
  35. ^ Bostock, John; Riley, Henry T.; Pliny the Elder (1855). The natural history of Pliny. London: H. G. Bohn. p. 64.{{cite book}}: CS1 maint: multiple names: authors list (link)
  36. ISBN 978-0-674-99078-4.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  37. ^
    ISBN 978-0-387-30800-5
    .
  38. ISBN 978-0-8089-2371-8
    .
  39. ^
    ISBN 978-0-03-910284-5
    .
  40. ^
    ISBN 978-0-521-61714-7
    .
  41. PMID 21708724
    .
  42. ISBN 978-0-87605-606-6
    .
  43. S2CID 10921118
    .
  44. ^ Eveleth, Rose (20 February 2013). "Could a Whale Accidentally Swallow You? It Is Possible". Smithsonian. Retrieved 12 April 2014.
  45. ISBN 978-0-935848-47-2
    .
  46. S2CID 22477083
    .
  47. ISBN 978-0-03-056747-6
    .
  48. doi:10.1093/mollus/64.2.249
    .
  49. ^ Appleton C. C., Forbes A. T.& Demetriades N. T. (2009). "The occurrence, bionomics and potential impacts of the invasive freshwater snail Tarebia granifera (Lamarck, 1822) (Gastropoda: Thiaridae) in South Africa" Archived 2014-04-16 at the Wayback Machine. Zoologische Mededelingen 83.
  50. ISBN 978-3-7643-5076-5
    .

External links

Wikimedia Commons has media related to Esophagus.
Look up esophagus in Wiktionary, the free dictionary.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Esophagus&oldid=1206260258"