document_title: Small intestine

question_text: where does most digestion take place in the small intestine

text: Small intestine

text: Structure[edit]

text: Size[edit]

text: The length of the small intestine can vary greatly, from as short as 2.75 m (9.0 ft) to as long as 10.49 m (34.4 ft).[3] The average length in a living person is 3m-5m.[4][5] The length depends both on how tall the person is and how the length is measured.[3] Taller people generally have a longer small intestine and measurements are generally longer after death and when the bowel is empty.[3]

text: It is approximately 1.5 cm in diameter in newborns after 35 weeks of gestational age,[6] and 2.5–3 cm (1 inch) in diameter in adults. On abdominal X-rays, the small intestine is considered to be abnormally dilated when the diameter exceeds 3 cm.[7][8] On CT scans, a diameter of over 2.5 cm is considered abnormally dilated.[7][9] The surface area of the human small intestinal mucosa, due to enlargement caused by folds, villi and microvilli, averages 30 square meters.[10]

text: Parts[edit]

text: The small intestine is divided into three structural parts.

text:
The duodenum is a short structure ranging from 20 cm (7.9 inches) to 25 cm (9.8 inches) in length, and shaped like a "C".[11] It surrounds the head of the pancreas. It receives gastric chyme from the stomach, together with digestive juices from the pancreas (digestive enzymes) and the liver (bile). The digestive enzymes break down proteins and bile and emulsify fats into micelles. The duodenum contains Brunner's glands, which produce a mucus-rich alkaline secretion containing bicarbonate. These secretions, in combination with bicarbonate from the pancreas, neutralize the stomach acids contained in gastric chyme.
The jejunum is the midsection of the small intestine, connecting the duodenum to the ileum. It is about 2.5 m long, and contains the plicae circulares, and villi that increase its surface area. Products of digestion (sugars, amino acids, and fatty acids) are absorbed into the bloodstream here. The suspensory muscle of duodenum marks the division between the duodenum and the jejunum.
The ileum: The final section of the small intestine. It is about 3 m long, and contains villi similar to the jejunum. It absorbs mainly vitamin B12 and bile acids, as well as any other remaining nutrients. The ileum joins to the cecum of the large intestine at the ileocecal junction.

text: The jejunum and ileum are suspended in the abdominal cavity by mesentery. The mesentery is part of the peritoneum. Arteries, veins, lymph vessels and nerves travel within the mesentery.[12]

text: Blood supply[edit]

text: The small intestine receives a blood supply from the coeliac trunk and the superior mesenteric artery. These are both branches of the aorta. The duodenum receives blood from the coeliac trunk via the superior pancreaticoduodenal artery and from the superior mesenteric artery via the inferior pancreaticoduodenal artery. These two arteries both have anterior and posterior branches that meet in the midline and anastomose. The jejunum and ileum receive blood from the superior mesenteric artery.[13] Branches of the superior mesenteric artery form a series of arches within the mesentery known as arterial arcades, which may be several layers deep. Straight blood vessels known as vasa recta travel from the arcades closest to the ileum and jejunum to the organs themselves.[13]

text: Histology[edit]

text: The three sections of the small intestine look similar to each other at a microscopic level, but there are some important differences. The parts of the intestine are as follows:

text:
Layer
Duodenum
Jejunum
Ileum

Serosa
1st part serosa, 2nd–4th adventitia
Normal
Normal

Muscularis externa
Longitudinal and circular layers, with Auerbach's (myenteric) plexus in between
Same as duodenum
Same as duodenum

Submucosa
Brunner's glands and Meissner's (submucosal) plexus
No BG
No BG

Mucosa: muscularis mucosae
Normal
Normal
Normal

Mucosa: lamina propria
No PP
No PP
Peyer's patches

Mucosa: intestinal epithelium
Simple columnar. Contains goblet cells, Paneth cells
Similar to duodenum
 ?

text: Development[edit]

text: The small intestine develops from the midgut of the primitive gut tube.[14] By the fifth week of embryological life, the ileum begins to grow longer at a very fast rate, forming a U-shaped fold called the primary intestinal loop. The loop grows so fast in length that it outgrows the abdomen and protrudes through the umbilicus. By week 10, the loop retracts back into the abdomen. Between weeks six and ten the small intestine rotates anticlockwise, as viewed from the front of the embryo. It rotates a further 180 degrees after it has moved back into the abdomen. This process creates the twisted shape of the large intestine.[14]

text: Function[edit]

text: Food from the stomach is allowed into the duodenum through the pylorus by a muscle called the pyloric sphincter.

text: Digestion[edit]

text: The small intestine is where most chemical digestion takes place. Many of the digestive enzymes that act in the small intestine are secreted by the pancreas and liver and enter the small intestine via the pancreatic duct. Pancreatic enzymes and bile from the gallbladder enter the small intestine in response to the hormone cholecystokinin, which is produced in the small intestine in response to the presence of nutrients. Secretin, another hormone produced in the small intestine, causes additional effects on the pancreas, where it promotes the release of bicarbonate into the duodenum in order to neutralize the potentially harmful acid coming from the stomach.

text: The three major classes of nutrients that undergo digestion are proteins, lipids (fats) and carbohydrates:

text:
Proteins are degraded into small peptides and amino acids before absorption.[15] Chemical breakdown begins in the stomach and continues in the small intestine. Proteolytic enzymes, including trypsin and chymotrypsin, are secreted by the pancreas and cleave proteins into smaller peptides. Carboxypeptidase, which is a pancreatic brush border enzyme, splits one amino acid at a time. Aminopeptidase and dipeptidase free the end amino acid products.
Lipids (fats) are degraded into fatty acids and glycerol. Pancreatic lipase breaks down triglycerides into free fatty acids and monoglycerides. Pancreatic lipase works with the help of the salts from the bile secreted by the liver and stored in the gall bladder. Bile salts attach to triglycerides to help emulsify them, which aids access by pancreatic lipase. This occurs because the lipase is water-soluble but the fatty triglycerides are hydrophobic and tend to orient towards each other and away from the watery intestinal surroundings. The bile salts emulsify the triglycerides in the watery surroundings until the lipase can break them into the smaller components that are able to enter the villi for absorption.
Some carbohydrates are degraded into simple sugars, or monosaccharides (e.g., glucose). Pancreatic amylase breaks down some carbohydrates (notably starch) into oligosaccharides. Other carbohydrates pass undigested into the large intestine and further handling by intestinal bacteria. Brush border enzymes take over from there. The most important brush border enzymes are dextrinase and glucoamylase, which further break down oligosaccharides. Other brush border enzymes are maltase, sucrase and lactase. Lactase is absent in some adult humans and, for them, lactose, like most poly-saccharides, is not digested in the small intestine. Some carbohydrates, such as cellulose, are not digested at all, despite being made of multiple glucose units. This is because the cellulose is made out of beta-glucose, making the inter-monosaccharidal bindings different from the ones present in starch, which consists of alpha-glucose. Humans lack the enzyme for splitting the beta-glucose-bonds, something reserved for herbivores and bacteria from the large intestine.

text: Absorption[edit]

text: Digested food is now able to pass into the blood vessels in the wall of the intestine through either diffusion or active transport. The small intestine is the site where most of the nutrients from ingested food are absorbed. The inner wall, or mucosa, of the small intestine is lined with simple columnar epithelial tissue. Structurally, the is covered in wrinkles or folds called plicae circulares, which are considered permanent features in the wall of the organ. They are distinct from rugae which are considered non-permanent or temporary allowing for distention and contraction. From the plicae circulares project microscopic finger-like pieces of tissue called villi (Latin for "shaggy hair"). The individual epithelial cells also have finger-like projections known as microvilli. The functions of the plicae circulares, the villi, and the microvilli are to increase the amount of surface area available for the absorption of nutrients, and to limit the loss of said nutrients to intestinal fauna.

text: Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface. The epithelial cells of the villi transport nutrients from the lumen of the intestine into these capillaries (amino acids and carbohydrates) and lacteals (lipids). The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by our body. The material that remains undigested and unabsorbed passes into the large intestine.

text: Absorption of the majority of nutrients takes place in the jejunum, with the following notable exceptions:

text:
Iron is absorbed in the duodenum.
Vitamin B12 and bile salts are absorbed in the terminal ileum.
Water and lipids are absorbed by passive diffusion throughout the small intestine.
Sodium bicarbonate is absorbed by active transport and glucose and amino acid co-transport.
Fructose is absorbed by facilitated diffusion.

text: Immunological[edit]

text: The small intestine supports the body's immune system.[16] The presence of gut flora appears to contribute positively to the host's immune system. Peyer's patches, located within the ileum of the small intestine, are an important part of the digestive tract's local immune system. They are part of the lymphatic system, and provide a site for antigens from potentially harmful bacteria or other microorganisms in the digestive tract to be sampled, and subsequently presented to the immune system.[17]

text: Gene and protein expression[edit]

text: About 20,000 protein coding genes are expressed in human cells and 70 % of these genes are expressed in the normal duodenum.[18][19] Some 300 of these genes are more specifically expressed in the duodenum with very few genes expressed only in the small intestine. The corresponding specific proteins are expressed in glandular cells of the mucosa, such as fatty acid binding protein FABP6. Most of the more specifically expressed genes in the small intestine are also expressed in the duodenum, for example FABP2 and the DEFA6 protein expressed in secretory granules of Paneth cells.[20]

text: Clinical significance[edit]

text: The small intestine is a complex organ, and as such, there are a very large number of possible conditions that may affect the function of the small bowel. A few of them are listed below, some of which are common, with up to 10% of people being affected at some time in their lives, while others are vanishingly rare.

text:
Small intestine obstruction or obstructive disorders

Paralytic ileus
Volvulus
Hernia
Intussusception
Adhesions
Obstruction from external pressure
Obstruction by masses in the lumen (foreign bodies, bezoar, gallstones)

Infectious diseases

Giardiasis
Ascariasis
Tropical sprue
Tape worm (Diphyllobothrium latum, Taenia solium, Hymenolepsis nana)
Hookworm (e.g. Necator americanus, Ancylostoma duodenale)
Nematodes (e.g. Ascaris lumbricoides)
Other Protozoa (e.g. Cryptosporidium parvum, Cyclospora, Microsporidia, Entamoeba histolytica)
Bacterial infections

Enterotoxigenic Escherichia coli
Salmonella enterica
Campylobacter
Shigella
Yersinia
Clostridium difficile (antibiotic-associated colitis, Pseudomembranous colitis)
Mycobacterium (Mycobacterium avium paratuberculosis, disseminated Mycobacterium tuberculosis)
Whipple's disease
Vibrio (cholera)
Enteric (typhoid) fever (Salmonella enterica var. typhii) and paratyphoid fever
Bacillus cereus
Clostridium perfringens (gas gangrene)

Viral infections

Rotavirus
Norovirus
Astrovirus
Adenovirus
Calicivirus

Neoplasms (cancers)

Adenocarcinoma
Carcinoid
Gastrointestinal stromal tumor (GIST)
Lymphoma
Sarcoma
Leiomyoma
Metastatic tumors, especially SCLC or melanoma

Developmental, congenital or genetic conditions

Duodenal (intestinal) atresia
Hirschsprung's disease
Meckel's diverticulum
Pyloric stenosis
Pancreas divisum
Ectopic pancreas
Enteric duplication cyst
Situs inversus
Cystic fibrosis
Malrotation
Persistent urachus
Omphalocele
Gastroschisis
Disaccharidase (lactase) deficiencies
Primary bile acid malabsorption
Gardner syndrome
Familial adenomatous polyposis syndrome (FAP)

Other conditions

Crohn's disease, and the more general inflammatory bowel disease
Typhlitis (neutropenic colitis in the immunosuppressed
Coeliac disease (sprue or non-tropical sprue)
Mesenteric ischemia
Embolus or thrombus of the superior mesenteric artery or the superior mesenteric vein
Arteriovenous malformation
Gastric dumping syndrome
Irritable bowel syndrome
Duodenal (peptic) ulcers
Gastrointestinal perforation
Hyperthyroidism
Diverticulitis
Radiation enterocolitis
Mesenteric cysts
Peritoneal Infection
Sclerosing retroperitonitis
Small intestinal bacterial overgrowth

text: Other animals[edit]

text: The small intestine is found in all tetrapods and also in teleosts, although its form and length vary enormously between species. In teleosts, it is relatively short, typically around one and a half times the length of the fish's body. It commonly has a number of pyloric caeca, small pouch-like structures along its length that help to increase the overall surface area of the organ for digesting food. There is no ileocaecal valve in teleosts, with the boundary between the small intestine and the rectum being marked only by the end of the digestive epitheliu [21]

text: In tetrapods, the ileocaecal valve is always present, opening into the colon. The length of the small intestine is typically longer in tetrapods than in teleosts, but is especially so in herbivores, as well as in mammals and birds, which have a higher metabolic rate than amphibians or reptiles. The lining of the small intestine includes microscopic folds to increase its surface area in all vertebrates, but only in mammals do these develop into true villi.[21]

text: The boundaries between the duodenum, jejunum, and ileum are somewhat vague even in humans, and such distinctions are either ignored when discussing the anatomy of other animals, or are essentially arbitrary.[21]

text: There is no small intestine as such in non-teleost fish, such as sharks, sturgeons, and lungfish. Instead, the digestive part of the gut forms a spiral intestine, connecting the stomach to the rectum. In this type of gut, the intestine itself is relatively straight, but has a long fold running along the inner surface in a spiral fashion, sometimes for dozens of turns. This valve greatly increases both the surface area and the effective length of the intestine. The lining of the spiral intestine is similar to that of the small intestine in teleosts and non-mammalian tetrapods.[21]

text: In lampreys, the spiral valve is extremely small, possibly because their diet requires little digestion. Hagfish have no spiral valve at all, with digestion occurring for almost the entire length of the intestine, which is not subdivided into different regions.[21]

text: Society and culture[edit]

text: In traditional Chinese medicine, the small intestine is a yang organ.[22]

text: Additional images[edit]

text:
Small intestine in situ, greater omentum folded upwards.

Third state of the development of the intestinal canal and peritoneum, seen from in front (diagrammatic). The mode of preparation is the same as in Fig 400

Second stage of development of the intestinal canal and peritoneum, seen from in front (diagrammatic). The liver has been removed and the two layers of the ventral mesogastrium (lesser omentum) have been cut. The vessels are represented in black and the peritoneum in the reddish tint.

First stage of the development of the intestinal canal and the peritoneum, seen from the side (diagrammatic). From colon 1 the ascending and transverse colon will be formed and from colon 2 the descending and sigmoid colons and the rectum.


document_title: Pulp (tooth)

question_text: where is the nerve located in a tooth

question_tokens: where is the nerve located in a tooth

root

text: Pulp (tooth)

text: Anatomy[edit]

text: The pulp is the neurovascular bundle central to each tooth, permanent or primary. It comprises a central pulp chamber, pulp horns and radicular canals. The large mass of pulp is contained within the pulp chamber, which is contained in and mimics the overall shape of the crown of the tooth.[2] Because of continuous deposition of dentin, the pulp chamber becomes smaller with age. This is not uniform throughout the coronal pulp but progresses faster on the floor than on the roof or side walls.

tag: p

text: Radicular pulp canals extend down from the cervical region of the crown to the root apex. They are not always straight but vary in shape, size and number. They are continuous with the periapical tissues through the apical foramen or foramina.

text: The total volumes of all the permanent teeth organs is 0.38cc and the mean volume of a single adult human pulp is 0.02cc.

text: Accessory canals are pathways from the radicular pulp, extending laterally through the dentin to the periodontal tissue seen especially in the apical third of the root. Accessory canals are also called lateral canals, because they are usually located on the lateral surface of the roots of the teeth.

text: Development[edit]

text: The pulp has a background similar to that of dentin, because both are derived from the dental papilla of the tooth germ. During odontogenesis, when the dentin forms around the dental papilla, the innermost tissue is considered pulp.[3]

text: Internal structure[edit]

text: The central region of the coronal and radicular pulp contains large nerve trunks and blood vessels.

text: This area is lined peripherally by a specialized odontogenic area which has four layers (from innermost to outermost):

text:
Pulpal core, which is in the center of the pulp chamber with many cells and an extensive vascular supply; except for its location, it is very similar to the cell-rich zone.
Cell rich zone; which contains fibroblasts and undifferentiated mesenchymal cells.
Cell free zone (zone of Weil) which is rich in both capillaries and nerve networks.
Odontoblastic layer; outermost layer which contains odontoblasts and lies next to the predentin and mature dentin.

tag: ol

text: Cells found in the dental pulp include fibroblasts (the principal cell), odontoblasts, defence cells like histiocytes, macrophage, granulocytes, mast cells and plasma cells.The nerve plexus of Raschkow is located central to the cell-rich zone.[3]

text: The plexus of Raschkow[edit]

text: The plexus of Raschkow monitors painful sensations. By virtue of their peptide content they also play important functions in inflammatory events and subsequent tissue repair. There are two types of nerve fiber that mediate the sensation of pain: A-fibers conduct rapid and sharp pain sensations and belong to the myelinated group, whereas C-fibers are involved in dull aching pain and are thinner and unmyelinated. The A-fibers, mainly of the A-delta type, are preferentially located in the periphery of the pulp, where they are in close association with the odontoblasts and extend fibers to many but not all dentinal tubules. The C-fibers typically terminate in the pulp tissue proper, either as free nerve endings or as branches around blood vessels. Sensory nerve fibers that originate from inferior and superior alveolar nerves innervate the odontoblastic layer of the pulp cavity. These nerves enter the tooth through the apical foramen as myelinated nerve bundles. They branch to form the subodontoblastic nerve plexus of Raschkow which is separated from the odontoblasts by a cell-free zone of Weil, therefore this plexus lies between the cell free and cell rich zones of the pulp.

text: Functions[edit]

text: The primary function of the dental pulp is to form dentin (by the odontoblasts).

text: Other functions include:

text:
Nutritive: the pulp keeps the organic components of the surrounding mineralized tissue supplied with moisture and nutrients;
Protective/Sensory: extremes in temperature, pressure, or trauma to the dentin or pulp are perceived as pain;
Defensive/reparative : the formation of reparative or tertiary dentin (by the odontoblasts);
Formative: cells of the pulp produce dentin which surrounds and protects the pulpal tissue.

tag: ul

text: Pulp Testing[edit]

text: [4] Dental pulp testing is an investigation that is used to assess the pulpal vitality. This assessment is crucial in order to plan the most suitable endodontic treatment for the tooth. Traditionally, the pulp’s condition is inspected via a pulp sensibility test, which extrapolates pulpal status based on its sensory response towards stimuli such as heat and cold. Listed are the diagnostic techniques most commonly used to assess the pulpal sensitivity:

text: 1. Thermal Test

text: a. Heat test – A heated Gutta-Percha stick is the most commonly used method for heat testing.

text: b. Cold Test – Ethyl Chloride, frozen carbon dioxide (dry ice) and Dichlorodifluoromethane (Freon) are used as cold testing material.

text: 2.[5] Electric pulp testing – Health status of the pulp is tested by electrical excitations of neural elements within the pulp.

text: 3. Anaesthesia testing – A single tooth is anaesthetized at a time until the pain is diminished. If the pain continues, the procedure is repeated to the next tooth mesial to it. It is continued until the pain is gone. If source of pain cannot be determined, the same technique on the opposite arch is repeated.

text: 4. Bite test – In this test patient is asked to bite on a hard object such as cotton swab, tooth pick, or orange wood stick. Pain on biting may indicate a fractured tooth.

text: 5. Test cavity – This technique is only used when the results produced by all other methods above are inconclusive. High speed burs are used to make the test cavity. Patient is asked whether painful sensation is felt during drilling. Pulpal vitality is indicated if there is any sensitivity or pain felt by the patient.

text: However, these traditional testing methods have some disadvantages compared to the pulp vitality test in which the pulp blood circulation is evaluated instead. Major limitations of the traditional pulp sensitivity test include:

text:
Likelihood to elicit an uncomfortable and sometimes painful sensation in the patient.
May yield false positive or false negative results. These tests only indicate the pulpal sensory fibres' vitality but do not always reflect the stage and extent of pulpal disease.
Subjective nature of the test. The pulp sensibility test depends on the patient’s response to a particular stimulus and the dentist’s interpretation of that response.

text: Recent studies have suggested that blood circulation is the most reliable factor in testing the pulp’s vitality. The recent diagnostic methods to assess the vascular response of the pulp include:

text: 1. Laser Doppler Flowmetry

text: 2. Pulse Oximetry

text: 3. Dual Wavelength Spectrophotometry

text: Reversible Pulpitis[edit]

text: A mild to moderate inflammation of dental pulp caused by any momentary irritation or stimulant whereby no pain is felt upon removal of stimulants.[6] Nevertheless, there is no significant radiographic changes in the periapical region hence further examination is mandatory to ensure that the dental pulp has returned to its normal healthy state.[7]

text: Common Causes [6][edit]

text: - Bacterial infection from caries

text: - Thermal shock

text: - Trauma

text: - Excessive dehydration of a cavity during restoration

text: - Irritation of exposed dentine

text: Symptoms [6][edit]

text: - Temporary post-restoration sensitivity

text: - Short sharp pain due to a stimulant

text: Prevention [6][edit]

text: - Regular check-ups for carcinogenic or non-carcinogenic caries

text: - When preparing cavities, dehydrate with adequate amount of alcohol or chloroform and apply enough varnish to protect the pulp

text: Irreversible Pulpitis[edit]

text: Pain occurs spontaneously if the reversible pulpitis hasn’t been treated well leaving the cause of inflammation. Usually occurs as a result of cracked tooth following trauma,[8] extensive restorations,[7] dental caries.[8] Incapable of healing and hence root canal treatment is required. It can present as symptomatic irreversible pulpitis or asymptomatic irreversible pulpitis.[7]

text: Symptoms

text: The intensity of pain varies at different temperatures. A person may experience

text:
A spontaneous, high intensity pain while eating hot and cold products(thermal stimulus).[7][8]
A lingering pain which often lasts for 30 seconds or longer after the stimulus is removed.[7][8]
Referred pain[7]
No tender to percussion[7]

text: Treatments: Require endodontic (root canal) treatment or tooth extraction. In endodontic therapy, removal of the inflamed pulp relieves the pain. The empty root canal system is then obturated with Gutta-Percha which is a rubber material that acts as a pressure and pain reliever.[8]

text: Complications[edit]

text: Pulp acts as a security and alarm system for a tooth. Slight decay in tooth structure not extending to the dentin may not alarm the pulp but as the dentin gets exposed, either due to dental caries or trauma, sensitivity starts. The dentinal tubules pass the stimulus to odontoblastic layer of the pulp which in turns triggers the response. This mainly responds to cold. At this stage simple restorations can be performed for treatment. As the decay progresses near the pulp the response also magnifies and sensation to a hot diet as well as cold gets louder. At this stage indirect pulp capping might work for treatment but at times it is impossible to clinically diagnose the extent of decay, pulpitis may elicit at this stage. Carious dentin by dental decay progressing to pulp may get fractured during mastication (chewing food) causing direct trauma to the pulp hence eliciting pulpitis.

text: The inflammation of the pulp is known as pulpitis. Pulpitis can be extremely painful and in serious cases calls for root canal therapy or endodontic therapy.[9] Traumatized pulp starts an inflammatory response but due to the hard and closed surroundings of the pulp pressure builds inside the pulp chamber compressing the nerve fibres and eliciting extreme pain (acute pulpitis). At this stage the death of the pulp starts which eventually progresses to periapical abscess formation (chronic pulpitis).

text: The pulp horns recede with age. Also with increased age, the pulp undergoes a decrease in intercellular substance, water, and cells as it fills with an increased amount of collagen fibers.This decrease in cells is especially evident in the reduced number of undifferentiated mesenchymal cells. Thus, the pulp becomes more fibrotic with increased age, leading to a reduction in the regenerative capacity of the pulp due its loss of these cells. Also, the overall pulp cavity may be smaller by the addition of secondary or tertiary dentin, thus causing pulp recession. The lack of sensitivity associated with older teeth is due to receded pulp horns, pulp fibrosis, addition of dentin, or possibly all these age-related changes; many times restorative treatment can be performed without local anesthesia on older dentitions.[2]


document_title: Centaur

question_text: what is the half horse half man called in narnia

text: Centaur

text: Mythology[edit]

text: Origin[edit]

text: The centaurs were usually said to have been born of Ixion and Nephele (the cloud made in the image of Hera). Another version, however, makes them children of a certain Centaurus, who mated with the Magnesian mares. This Centaurus was either himself the son of Ixion and Nephele (inserting an additional generation) or of Apollo and Stilbe, daughter of the river god Peneus. In the later version of the story his twin brother was Lapithes, ancestor of the Lapiths, thus making the two warring peoples cousins.

text: Centaurs were said to have inhabited the region of Magnesia and Mount Pelion in Thessaly, the Foloi oak forest in Elis, and the Malean peninsula in southern Laconia.

text: Another tribe of centaurs was said to have lived on Cyprus. According to Nonnus, they were fathered by Zeus, who, in frustration after Aphrodite had eluded him, spilled his seed on the ground of that land. Unlike those of mainland Greece, the Cyprian centaurs were horned.[3][4]

text: There were also the Lamian Pheres, twelve rustic daimones of the Lamos river. They were set by Zeus to guard the infant Dionysos, protecting him from the machinations of Hera but the enraged goddess transformed them into ox-horned Centaurs. The Lamian Pheres later accompanied Dionysos in his campaign against the Indians.[5]

text: Centaurs subsequently featured in Roman mythology, and were familiar figures in the medieval bestiary. They remain a staple of modern fantastic literature. The centaur's half-human, half-horse composition has led many writers to treat them as liminal beings, caught between the two natures, embodied in contrasted myths, both as the embodiment of untamed nature, as in their battle with the Lapiths (their kin), or conversely as teachers, like Chiron.

text: Centauromachy[edit]

text: The Centaurs are best known for their fight with the Lapiths, which was caused by their attempt to carry off Hippodamia and the rest of the Lapith women on the day of Hippodamia's marriage to Pirithous, king of the Lapithae, himself the son of Ixion. The strife among these cousins is a metaphor for the conflict between the lower appetites and civilized behavior in humankind. Theseus, a hero and founder of cities, who happened to be present, threw the balance in favour of the right order of things, and assisted Pirithous. The Centaurs were driven off or destroyed.[6][7][8] Another Lapith hero, Caeneus, who was invulnerable to weapons, was beaten into the earth by Centaurs wielding rocks and the branches of trees. Centaurs are thought of in many Greek myths as wild as untamed horses. Like the Titanomachy, the defeat of the Titans by the Olympian gods, the contests with the Centaurs typify the struggle between civilization and barbarism.

text: The Centauromachy is most famously portrayed in the Parthenon metopes by Phidias and in a Renaissance-era sculpture by Michelangelo.

text: Other depictions in classical art[edit]

text: The tentative identification of two fragmentary Mycenaean terracotta figures as centaurs, among the extensive Mycenaean pottery found at Ugarit, suggests a Bronze Age origin for these creatures of myth.[9] A painted terracotta centaur was found in the "Hero's tomb" at Lefkandi, and by the Geometric period, centaurs figure among the first representational figures painted on Greek pottery. An often-published Geometric period bronze of a warrior face-to-face with a centaur is at the Metropolitan Museum of Art.[10]

text: In Greek art of the Archaic period, centaurs are depicted in three different forms. Some centaurs are depicted with a human torso attached to the body of a horse at the withers, where the horse's neck would be; this form, designated "Class A" by Professor Baur, later became standard. "Class B" centaurs are depicted with a human body and legs, joined at the waist with the hindquarters of a horse; in some cases centaurs of both types appear together. A third type, designated "Class C", depicts centaurs with human forelegs terminating in hooves. Baur describes this as an apparent development of Aeolic art, which never became particularly widespread.[11] At a later period, paintings on some amphoras depict winged centaurs.

text: Centaurs were also frequently depicted in Roman art. A particularly famous example is the pair of centaurs drawing the chariot of Constantine the Great and his family, in the Great Cameo of Constantine (circa AD 314-16), which embodies wholly pagan imagery, and contrasts sharply with the popular image of Constantine as the patron of early Christianity.[12][13]

text: Theories of origin[edit]

text: The most common theory holds that the idea of centaurs came from the first reaction of a non-riding culture, as in the Minoan Aegean world, to nomads who were mounted on horses. The theory suggests that such riders would appear as half-man, half-animal (Bernal Díaz del Castillo reported that the Aztecs had this misapprehension about Spanish cavalrymen).[14] Horse taming and horseback culture arose first in the southern steppe grasslands of Central Asia, perhaps approximately in modern Kazakhstan.

text: The Lapith tribe of Thessaly, who were the kinsmen of the Centaurs in myth, were described as the inventors of horse-back riding by Greek writers. The Thessalian tribes also claimed their horse breeds were descended from the centaurs.

text: Of the various Classical Greek authors who mentioned centaurs, Pindar was the first who describes undoubtedly a combined monster.[15] Previous authors (Homer) tend to use words such as pheres (cf. theres, "beasts")[16] that could also mean ordinary savage men riding ordinary horses, though Homer does specifically refer to a centaur ("kentauros") in the Odyssey [17] Contemporaneous representations of hybrid centaurs can be found in archaic Greek art.

text: Lucretius in his first century BC philosophical poem On the Nature of Things denied the existence of centaurs based on their differing rate of growth. He states that at the age of three years horses are in the prime of their life while, at three humans are still little more than babies, making hybrid animals impossible.[18]

text: Robert Graves (relying on the work of Georges Dumézil,[19] who argued for tracing the centaurs back to the Indian gandharva), speculated that the centaurs were a dimly remembered, pre-Hellenic fraternal earth cult who had the horse as a totem.[20] A similar theory was incorporated into Mary Renault's The Bull from the Sea. Kinnaras, another half-man half-horse mythical creature from the Indian mythology, appeared in various ancient texts, arts as well as sculptures from all around India. It is shown as a horse with the torso of a man in place of where the horse's head has to be, that is similar to a Greek centaur.[21][22]

text: The Greek word kentauros is generally regarded as of obscure origin.[23] The etymology from ken – tauros, "piercing bull-stickers" was a euhemerist suggestion in Palaephatus' rationalizing text on Greek mythology, On Incredible Tales (Περὶ ἀπίστων): mounted archers from a village called Nephele eliminating a herd of bulls that were the scourge of Ixion's kingdom.[24] Another possible related etymology can be "bull-slayer".[25] Some[who?] say that the Greeks took the constellation of Centaurus, and also its name "piercing bull", from Mesopotamia, where it symbolized the god Baal who represents rain and fertility, fighting with and piercing with his horns the demon Mot who represents the summer drought. In Greece, the constellation of Centaurus was noted by Eudoxus of Cnidus in the fourth century BC and by Aratus in the third century.

text: Indian centaur[edit]

text: In a popular legend associated with Pazhaya Sreekanteswaram Temple in Thiruvananthapuram, the curse of a saintly Brahmin transformed a handsome Yadava prince into a creature having a horse's body with the prince's head, arms and torso in place of the head and neck of the horse.

text: Female centaurs[edit]

text: Though female centaurs, called centaurides or centauresses, are not mentioned in early Greek literature and art, they do appear occasionally in later antiquity. A Macedonian mosaic of the 4th century BC is one of the earliest examples of the centauress in art.[26] Ovid also mentions a centauress named Hylonome[i] who committed suicide when her husband Cyllarus was killed in the war with the Lapiths.[27]

text: Persistence in the medieval world[edit]

text: Centaurs preserved a Dionysian connection in the 12th century Romanesque carved capitals of Mozac Abbey in the Auvergne, where other capitals depict harvesters, boys riding goats (a further Dionysiac theme) and griffins guarding the chalice that held the wine.

text: Centaurs are shown on a number of Pictish carved stones from north-east Scotland, erected in the 8th–9th centuries AD (e.g., at Meigle, Perthshire). Though outside the limits of the Roman Empire, these depictions appear to be derived from Classical prototypes.

text: Jerome's version of the Life of St Anthony the Great, the hermit monk of Egypt, written by Athanasius of Alexandria, was widely disseminated in the Middle Ages; it relates Anthony's encounter with a centaur, who challenged the saint but was forced to admit that the old gods had been overthrown. The episode was often depicted; in The Meeting of St Anthony Abbot and St Paul the Hermit by Stefano di Giovanni called "Sassetta",[28] of two episodic depictions in a single panel of the hermit Anthony's travel to greet the hermit Paul, one is his encounter along the pathway with the demonic figure of a centaur in a wood.

text: A centaur-like half-human half-equine creature called Polkan appeared in Russian folk art, and lubok prints of the 17th–19th centuries. Polkan is originally based on Pulicane, a half-dog from Andrea da Barberino's poem I Reali di Francia, which was once popular in the Slavonic world in prosaic translations.

text: Modern day[edit]

text: The John C. Hodges library at The University of Tennessee hosts a permanent exhibit of a "Centaur from Volos", in its library. The exhibit, made by sculptor Bill Willers, by combining a study human skeleton with the skeleton of a Shetland pony is entitled "Do you believe in Centaurs?" and was meant to mislead students in order to make them more critically aware, according to the exhibitors.[29]

text: Another exhibit by Willers is now on long-term display at the International Wildlife Museum in Tucson, Arizona. The full-mount skeleton of a Centaur, built by Skulls Unlimited International, is on display, along with several other fabled creatures, including the Cyclops, Unicorn and Griffin.

text: C.S. Lewis' The Chronicles of Narnia series depicts centaurs as the wisest and noblest of creatures. Narnian Centaurs are gifted at stargazing, prophecy, healing, and warfare, a fierce and valiant race always faithful to the High King Aslan the Lion. Lewis generally used the species to inspire awe in his readers.

text: In J.K. Rowling's Harry Potter series, centaurs live in the Forbidden Forest close to Hogwarts, preferring to avoid contact with humans. They live in societies called herds and are skilled at archery, healing and astrology, but like in the original myths, they are known to have some wild and barbarous tendencies. Although film depictions include very animalistic facial features, the reaction of the Hogwarts girls to Firenze suggests a more classical appearance.

text: With the exception of Chiron, the centaurs in Rick Riordan's Percy Jackson & the Olympians are seen as wild party-goers who use a lot of American slang. Chiron retains his mythological role as a trainer of heroes and is skilled in archery. In Riordan's subsequent series, Heroes of Olympus, another group of centaurs are depicted with more animalistic features (such as horns) and appear as villains, serving the Gigantes.

text: Philip Jose Farmer's World of Tiers series (1965) includes centaurs, called Half-Horses or Hoi Kentauroi. His creations address several of the metabolic problems of such creatures—how could the human mouth and nose intake sufficient air to sustain both itself and the horse body and, similarly, how could the human ingest sufficient food to sustain both parts.

text: Brandon Mull's Fablehaven series features Centaurs that live in an area called Grunhold. The Centaurs are portrayed as a proud, elitist group of beings that consider themselves superior to all other creatures. The fourth book also has a variation on the species called an Alcetaur, which is part man, part moose.

text: Centaur appears in the novel by John Updike (The Centaur, 1963). The author depicts a rural Pennsylvanian town as seen through the optics of the myth of Centaur. An unknown and marginalized local school teacher, just like the mythological Chiron did for Prometheus, gave up his life for the future of his son who had chosen to be an independent artist in New York.

text: Gallery[edit]

text:
Diosphos Painter, white-ground lekythos (500 BC)

Botticelli, Pallas and Centaur (1482–83)

Antonio Canova, Theseus Defeats the Centaur (1805-1819)

Prince Bova fights Polkan, Russian lubok (1860)

A bronze statue of a centaur, after the Furietti Centaurs