Vasculature – Small Intestine

by James Pickering, PhD

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    00:00 So let’s have a look at the vasculature in more detail now.

    00:03 We say that the jejunum receives greater supply of jejunal arteries than ileal arteries and it's slightly redder and it becomes pinker as we pass towards the large intestine.

    00:17 But let's just have a look and see what we have if we look at the vasculature.

    00:24 Now the jejunum and the ileum receive arterial blood from branches that comes from the superior mesenteric artery.

    00:32 Superior mesenteric artery originates from the aorta at approximately the L1 vertebral level.

    00:40 Remember the stomach will supply by arteries that come from the coeliac trunk that was at T12. So this superior mesenteric artery is coming from the aorta at about the L1 vertebral level. And what is does it gives rise to a whole series of blood vessels called jejunal and the ileal.

    01:00 The jejunal arteries, as you would expect, supply the jejunum. And the ileal arteries supply the ileum.

    01:07 Now obviously with there being a transition from jejunum to ileum, there is going to be a transition of jejunal arteries and ileal arteries. And what these do, these blood vessels run up through the mesentery. So the mesentery that's suspending the small intestine, these blood vessels run up through the mesentery. And as they do this, they form what are known as anastomotic loops.

    01:32 And these loops essentially parallel the small intestine.

    01:39 So if you imagine the superior mesenteric artery is running along the base of the mesentery.

    01:43 And it’s giving rise to the blood vessels that runs through the mesentery and these fan out the length of the root of the mesentery is about 5, 6, 7 cm.

    01:55 But the actual length of the small intestine is 6-7 meters.

    01:59 So these blood vessels fan out, and they fan out to run towards the free edge of the mesentery where the jejunum and ileum are located.

    02:11 And once they approach the free edge, they form these loops which run along the inside of the small intestine and they run parallel to it.

    02:21 And these are known as arterial arcades. We can see some in the diagram. They're running up towards running up towards, then you have these loops, these arcades which are running parallel to the small intestine.

    02:32 And then now you have got these arcades running parallel to the jejunum and the ileum.

    02:40 Small straight arteries come off them and these are called vase recta or straight arteries. They leave the arcade and go and supply the jejunum or the ileum. And the arcade is running parallel, these straight arteries then run towards the jejunum or the ileum themselves.

    02:58 So these are really important and we will go over these again when we look at the blood supply to the entire gastrointestinal tract in a later lecture.

    03:08 Venous drainage from these again is relatively straight forward but we will go over when we look at portal system in a later lecture. But if you are comfortable with the arterial supply then essentially the venous drainage is similar.

    03:22 They're going to drain into what’s known as the superior mesenteric vein and that forms part of the portal system.

    03:30 and we will look at that as it passes through the liver.

    03:34 We will look at the duodenum and its blood supply in lecture 9 when we look at the pancreas.

    About the Lecture

    The lecture Vasculature – Small Intestine by James Pickering, PhD is from the course Abdomen.

    Included Quiz Questions

    1. Superior mesenteric artery
    2. Inferior mesenteric artery
    3. Aorta
    4. Celiac artery
    5. Ileocolic artery
    1. L1
    2. L2
    3. T12
    4. T8
    5. T10

    Author of lecture Vasculature – Small Intestine

     James Pickering, PhD

    James Pickering, PhD

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