In anatomy Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy (zootomy) and plant anatomy (phytotomy). In some of its facets anatomy is closely related to embryology, comparative anatomy and comparative embryology, through common roots in, the mesentery is the double layer of peritoneum The peritoneum is the serous membrane that forms the lining of the abdominal cavity or the coelom — it covers most of the intra-abdominal organs — in higher vertebrates and some invertebrates (annelids, for instance). It is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum both supports the that suspends the jejunum The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum and ileum The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum from the posterior wall of the abdomen In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax (chest) and pelvis. The region enclosed by the abdomen is termed the abdominal cavity. In arthropods it is the most distal section of the body which lies behind the thorax or cephalothorax. Its meaning, however, is frequently extended to include double layers of peritoneum connecting various components of the abdominal cavity.
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Mesentery (proper)
The mesentery proper (i.e. the original definition) refers to the peritoneum responsible for connecting the jejunum The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum and ileum The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum (parts of the small intestine In vertebrates, the small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where the vast majority of digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to) to the back wall of the abdomen. Between the two sheets of peritoneum are blood vessels, lymph vessels, and nerves A peripheral nerve, or simply nerve is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system. In the central nervous system, the analogous structures are known as tracts. This allows these parts of the small intestine to move relatively freely within the abdominopelvic cavity. The brain, however, cannot map sensation accurately, so sensation is usually referred to the midline, an example of referred pain Referred pain is a term used to describe the phenomenon of pain perceived at a site adjacent to or at a distance from the site of an injury's origin. One of the best examples of this is during ischemia brought on by a myocardial infarction (heart attack) where pain is often felt in the neck, shoulders, and back rather than in the chest, the site.
Development
The mesentery is derived from what is known in the embryo as the dorsal mesentery The portion of mesentery attached to the greater curvature of the stomach is named the dorsal mesentery , and the part which suspends the colon is termed the mesocolon. The dorsal mesentery is larger than the ventral mesentery The cephalic portion of the septum transversum takes part in the formation of the diaphragm, while the caudal portion into which the liver grows forms the ventral mesentery, which gradually becomes other parts of the peritoneum. Most parts of the ventral mesentery are associated with the liver.
Mesentery (general)
Mesenteries are composed of two layers of peritoneum. The peritoneum that lies on the walls of the abdominopelvic cavity (parietal peritoneum) invaginates at certain parts, with an organ inside this invagination. This invaginated peritoneum (visceral peritoneum) will often surround all but a part of the organ ("bare area"), through which the organ transmits blood vessels and nerves. If this organ is invaginated far enough into the peritoneum, the visceral peritoneum will come in contact with itself, forming the organ's mesentery.
Mesenteries in the body:
- Mesentery (proper) - surrounds parts of the small intestine In vertebrates, the small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where the vast majority of digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to (the jejunum The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum and the ileum The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum)
- Mesocolon - surrounds parts of the colon The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a major role in absorption of foods and nutrients
- Meso-appendix - peritoneum of the vermiform appendix In human anatomy, the appendix (or vermiform appendix; also cecal appendix; also vermix) is a blind-ended tube connected to the cecum (or caecum), from which it develops embryologically. The cecum is a pouchlike structure of the colon. The appendix is located near the junction of the small intestine and the large intestine
- Transverse mesocolon - peritoneum of the transverse colon The transverse colon the longest and most movable part of the colon, passes with a downward convexity from the right hypochondrium region across the abdomen, opposite the confines of the epigastric and umbilical zones, into the left hypochondrium region, where it curves sharply on itself beneath the lower end of the spleen, forming the splenic or
- Sigmoid mesocolon - peritoneum of the sigmoid colon The sigmoid colon forms a loop that averages about 40 cm. in length, and normally lies within the pelvis, but on account of its freedom of movement it is liable to be displaced into the abdominal cavity. The sigmoid colon is the part of the large intestine which is closest to the rectum and anus
- Broad ligament of the uterus The broad ligament of the uterus is the wide fold of peritoneum that connects the sides of the uterus to the walls and floor of the pelvis - peritoneum of the uterus The uterus (from Latin "uterus" , plural uteruses or uteri) or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species. It is within the uterus that the fetus, uterine tubes, and ovaries The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in females are homologous to testes in males, in that they are both gonads and endocrine glands
Pathology
A lack of blood-supply to the mesentery causes mesenteric ischemia Mesenteric ischemia is a medical condition in which inflammation and injury of the small intestine result from inadequate blood supply.. Causes of the reduced blood flow can include changes in the systemic circulation (e.g. low blood pressure) or local factors such as constriction of blood vessels or a blood clot. It is more common in the elderly.
Invertebrate anatomy
In invertebrates An invertebrate is an animal without a backbone. The group includes 95% of all animal species — all animals except those in the chordate subphylum Vertebrata, the term mesentery is used for any tissue that divides the body cavity (coelom The coelom is a fluid filled cavity formed within the mesoderm. Coeloms developed in triploblasts but were subsequently lost in several lineages. Loss of coelom is correlated with reduction in body size. Coeloms are only ever present in triploblastic animals, though coelom is sometimes (incorrectly) used to refer to any developed digestive tract) into partitions.
Additional images
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Figure obtained by combining several successive sections of a human embryo of about the fourth week. |
Abdominal part of digestive tube and its attachment to the primitive or common mesentery. Human embryo of six weeks. |
Cookery
Among cooks, the mesentery is known as the crow.[1] In classical French cuisine French cuisine is a style of cooking originating from France, having developed from centuries of social and political change. The Middle Ages brought Guillaume Tirel, better known as Taillevent. The modern age, starting in the 17th century, however, saw a move toward fewer spices and more liberal usage of herbs and creamy ingredients, beginning, veal crow (French French is a Romance language spoken as a first language by about 136 million people worldwide. Around 190 million people speak French as a second language, and an additional 200 million speak it as an acquired foreign language. French speaking communities are present in 57 countries and territories. Most native speakers of the language live in: fraise de veau) is typically blanched then cooked in stock, and sometimes subsequently fried.[2]
Notes
- ^ Oxford English Dictionary, s.v. "crow", http://dictionary.oed.com/cgi/entry/50054748 (accessed 8 May 2009)
- ^ Escoffier 1979, 310
References
Escoffier, A. 1979. The Complete Guide to the Art of Modern Cookery. Trans. H. L. Cracknell. New York: Wiley, 1979.
External links
- SUNY Labs The State University of New York Health Science Center at Brooklyn, better known as SUNY Downstate Medical Center, is a public university and medical center located in central Brooklyn, New York. As the only academic center for health education, research, and patient care serving Brooklyn’s 2.5 million residents, SUNY Downstate has been an 39:01-0100
- jejunumileum at The Anatomy Lesson by Wesley Norman (Georgetown University Georgetown University is a Jesuit private university located in Georgetown, Washington, DC. Father John Carroll founded the school in 1789, though its roots extend back to 1634. While the school struggled financially in its early years, Georgetown expanded into a branched university after the American Civil War under the leadership of university)
- McGill
- -1724579760 at GPnotebook GPnotebook is a British medical database for general practitioners . It is an online encyclopaedia of medicine that provides an immediate reference resource for clinicians worldwide. The database consists of over 30,000 pages of information. GPnotebook is provided online by Oxbridge Solutions Limited
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Categories: Digestive system | Abdomen
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