Ischemia of which of the vessels would cause least damage:
Correct Answer: IMA
Description: Ans is 'c' i.e. IMA "Occlusion of the inferior mesenteric aery does not always result in irreversible ischaemia of the descending and sigmoid colon, because the marginal aery of the colon usually receives an adequate supply from the left branch of the middle colic aery. Moreover, the sigmoid aeries may be supplied by the superior rectal aery, which anastomoses with the middle and inferior rectal aeries. When ischaemia does occur, it is usually maximal in the proximal descending colon because this region is fuhest from the collateral aerial supplies."- Gray's Anatomy The colon is supplied by SMA and IMA which have extensive collateral circulation in the form of marginal aery and arc of Riolan The Marginal Aery of Drummond connects SMA and IMA, and forms a continuous arcade along the mesenteric border of the colon. The Arc of Riolan, also known as the Meandering Mesenteric aery, is another vascular arcade present in the colonic mesentery that connect the proximal Middle Colic aery (branch of SMA) with the proximal Left colic aery (branch of IMA). These collateral circulation in the form of Marginal aery and Arc of Riolan are able to sustain the pa of left colon in case of occlusion of the IMA. Moreever a distal collateral circulation also exists between the superior rectal aery (a branch of IMA) and the middle and inferior rectal aery (branches of the internal iliac aery). Celiac trunk and SMA do not have such rich collateral circulation and supply much more impoant pas than colon. Renal aery is an end aery, does not have any collaterals, so any injury or complete occlusion would lead to loss of the kidney.
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