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The mesenteric organ comprises the small intestinal mesentery (distal to the duodenojejunal flexure), the right mesocolon, the transverse mesocolon, the left mesocolon, the mesosigmoid and mesorectum. The gastrointestinal margin of the mesentery is that edge to which the gastrointestinal tract is attached. The region of gastrointestinal tract attached permits the naming of respective regions of the mesenteric organ. The ''transverse mesocolon'' is that region of the mesentery for which the transverse colon is attached to its gastrointestinal margin. The ''mesosigmoid'' is that region of the mesenteric organ to which the sigmoid colon is attached at the gastrointestinal mesenteric margin. A plane is defined as the interface between two contiguous structures.〔Coffey JC. Surgical anatomy and anatomic surgery - Clinical and scientific mutualism. ''Surgeon''. 2013 Aug;11(4):177–82.〕 For over a century, colorectal surgeons have exploited the plane formed by the mesentery and underlying fascia (i.e. Toldt's fascia) to separate the mesentery from the ''retroperitoneum''.〔Culligan K, Coffey JC, Kiran RP,Kalady M, Lavery IC, Remzi FH. The mesocolon: a prospective observational study. Colorectal Dis 2012;14:421e30.〕 Despite the central importance of this plane in gastrointestinal surgery (and the central importance of mesenteric and peritoneal anatomy) this field is frequently described as difficult and has remained largely misunderstood. Recent observations related to mesenteric and peritoneal anatomy confirmed a far simpler structure than was heretofore thought. In the first instance, the mesenteric organ is contiguous from duodenojejunal flexure to mesorectal level and not fragmented (as depicted by Frederick Treves).〔〔Treves F. Lectures on the anatomy of the intestinal canal and peritoneum in man. Br Med J 1885;1:580e3.〕〔Ellis H. The abdomen and pelvis. In:Ellis H, editor. Clinical anatomy: applied anatomy for students and junior doctors. 12th ed. Blackwell Science; 2010. p. 86〕〔McMinn RH. The gastrointestinal tract. In: McMinn RH, editor. Last’s anatomy: regional and applied. 9th ed.London: Langman Group Ltd; 1994. p. 331e42.〕 This realization recently provided significant educational, clinical and scientific opportunities. From a surgical perspective the concept of mesenteric contiguity greatly simplifies processes involved in resectional colorectal surgery by providing a clear anatomical roadmap for these. In addition it has permitted the ''canonical'' generation of nomenclature based entirely on anatomical observations (e.g. "total mesocolic excision").〔Sharad Karandikar, Sian Abbott. Open resection for colorectal cancer. Surgery (Oxford). Volume 32, Issue 4, April 2014,Pages 190–196.〕〔Culligan K, Remzi FH, Soop M, Coffey JC. Review of nomenclature in colonic surgery proposal of a standardized nomenclature based on mesocolic anatomy. Surgeon 2013;1:1e5.〕 In the following we briefly describe classic appraisals of mesenteric and peritoneal fold anatomy and the basis thereof. == Historical background == The classic interpretation of mesenteric and peritoneal fold anatomy stemmed from descriptions by Sir Frederick Treves in 1889 and depicted a fragmented structure that was vestigial at the level of the right and left colon.〔 Treves described the small bowel mesentery as ''inserting'' or ''attaching ''into the ''retroperitoneum'' along a line extending from the duodenojejunal flexure to the ileocaecal junction. The right and left mesocolon regressed and became vestigial as per Treves such that several commentators described these features as "abnormal as a cleft palate".〔McConnell, A. A., and Hardman, T.G.: Abnormalities of Fixation of Ascending Colon, Relation of Symptoms to Anatomical Findings. Brit. J. Surg., IO, 532, I923.〕〔Small,Andrew. The Surgical Correction of Anomalies in Fixation of the Ascending Colon. Ann Surg. 1937 Aug;106(2):230-41.〕 Their absence coupled by the presence of a transverse and sigmoid mesocolon meant that the mesenteric organ was fragmented, a description at odds with the surgical approach to colonic mobilisation and resection. In addition Treves described the transverse mesocolon as ''inserting'' or ''attaching'' along a line extending from hepatic to the splenic flexure. He described the mesosigmoid as ''inserting'' along a V-shaped line where the apex occurs approximately at the bifurcation of the common iliac artery. These descriptions have been indoctrinated in most reference anatomic, embryologic, surgical, and radiologic texts to the present day.〔Netter FH. Abdomen. In: Netter FH,editor. Atlas of human anatomy. Philadelphia, Pennsylvania: Saunders; 2007. p. 270e4.〕〔Standring S. Large intestine. In: Standring S, editor. Gray’s anatomy: the anatomical basis of clinical practice.40th ed. Philadelphia: Churchill Livingstone; 2008. p. 1137.〕〔Adams A, McConnell T. Abnormalities of fixation of the ascending colon: the relation of symptoms to anatomical findings.Br J Surg 1923;10:532e57.〕 Approximately 10 years prior to the descriptions of Treves, Carl Toldt described the right and left mesocolon as persisting into adulthood.〔Toldt C. Bau und wachstumsveranterungen der gekrose des menschlischen darmkanales. Denkschrdmathnaturwissensch 1879;41:1e56.〕〔Toldt C. An atlas of human anatomy for students and physicians 1919; vol. 4. 408.〕 In addition, Toldt described a fascial layer between mesocolon and ''retroperitoneum'' and that it was this particular layer that maintained the mesocolon and ''retroperitoneum separate''. Toldt’s findings were largely ignored as those of Treves were indoctrinated into mainstream literature. In 1942 Edward Condon repeated Toldt’s findings demonstrating the presence of a fascial layer between a persistent right (or left) mesocolon and ''retroperitoneum.''〔Congdon ED, Blumberg, R., Henry, W. Fasciae of fusion and elements of the fused enteric mesenteries in the human adult. American Journal of Anatomy 1942:70;251-79.〕 In 1986, the radiologist William Dodds suggested that the entire mesocolon is not secondarily ''retroperitoneal, but remains extra- retroperitoneal.''〔Dodds WJ, Darweesh RM, Lawson TL, et al. The retroperitoneal spaces revisited. AJR Am J Roentgenol.1986;147:1155-1161.〕'' Dodds postulated that and extra-retroperitoneal mesocolon and colon explains several radiologic anomalies. Dodds’s prescient suggestion and hypothesis were again largely ignored until recently when Culligan et al. confirmed that, in the adult, the entire small bowel and mesentery as well as colon and mesocolon, universally remain extra-retroperitoneal.''〔〔Culligan K, Walsh S, Dunne C et al. The Mesocolon: Histological and Electron Microscopic Characterization of the Mesenteric Attachment of the Colon Prior to and After Surgical Mobilization. Ann Surg. 2014 Jan 16. DOI:10.1097/SLA.0000000000000323.〕〔Coffey JC, Sehgal R, Culligan K, Dunne C, McGrath D, Lawes N, Walsh D. Terminology and nomenclature in colonic surgery: universal application of a rule-based approach derived from updates on mesenteric anatomy. Tech Coloproctol. 2014 Jun 27. DOI:10.1007/s10151-014-1184-2〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Transverse mesocolon」の詳細全文を読む スポンサード リンク
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