Foregut and Midgut – Autonomic Nerves of Abdominopelvic Organs

by James Pickering, PhD

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    00:01 So let's have a look at some examples. The foregut, The foregut (the stomach), stomach is an organ within the foregut.

    00:09 We can see here that in purple. we have the para-sympathetic input and we can see we have that via the vagus nerve.

    00:17 The anterior and the posterior vagal trunks.

    00:21 These enter the abdomen by passing through the diaphragm alongside the oesophagus and we can see here that the anterior vagal trunk is spreading out to supply this anterior surface of the stomach.

    00:35 We can see that the posterior vagal trunk is passing down at the back and that supplying the posterior surface of the stomach. So these are pre-ganglionic fibers. And they will then synapse with their post-ganglionic fiber which will then pass to the organ itself.

    00:55 But this occurs within the wall of that target organ.

    01:00 You can see the poster and anterior vagal trunks, they're giving branches that goes over to the liver and you can see it's dropping down into the pylorus.

    01:09 Well you can also see is this posterior vagal trunk is also giving a branch into this mesh, this plexus that is surrounding the coeliac trunk and this is the coeliac plexus.

    01:23 You can see either side of the coeliac trunk we have got our coeliac ganglia.

    01:27 And the coeliac ganglia are formed via the greater splanchnic nerve and that's we can see coming up here.

    01:37 So if we look at the para-sympathetic supply we have got some notes now. We can see in purple the anterior trunk is supplying the stomach and giving branches that go towards the liver and the duodenum. We can see the posterior vagal trunk is giving a branch that goes towards the coeliac plexus and the posterior surface of the stomach.

    02:01 We can see that the sympathetic supply is coming via what's known as the greater splanchnic nerve.

    02:09 The greater splanchnic nerve is going to leave the spinal cord from segments T5, T6, 7, 8, 9.

    02:21 Those spinal cord segments give rise to a sympathetic greater splanchnic nerve which passes through the coeliac ganglion.

    02:33 At the coeliac ganglion it will then synapse with post-ganglionic fibers that via the periarterial branches will pass to the stomach and there we have the autonomic supply to the stomach.

    02:46 Hopefully by the end we will appreciate by understanding this where this greater splanchinc nerve comes from is important, again referred pain.

    02:59 A similar situation happens for the midgut.

    03:03 The midgut being the small intestine and 2/3rds of the large intestine and we can see that the small intestine is going to have its autonomic supply via the superior mesenteric plexus.

    03:17 The superior mesenteric plexus which is going to be running along side the superior mesenteric artery.

    03:24 So what forms, what's the para-sympathetic input to this superior mesenteric plexus.

    03:32 Well for the midgut it's still the vagus nerve.

    03:36 The vagus nerve, the parts of the vagus nerve, of the posterior trunk that went to the coeliac plexus then carry on down the aorta, towards superior mesenteric plexus.

    03:47 So they just extended down and then via the periarterial branches they pass to the midgut.

    03:55 The sympathetic input, to the superior mesenteric plexus is via the superior mesenteric ganglion.

    04:07 The superior mesenteric ganglion is formed via the lesser and least splanchnic nerves. The lesser and least splanchnic nerves and these come from T10 - T12. It's thought that the lesser is T10 and 11 and the least is T12.

    04:24 I am not sure it's that important to remember that.

    04:28 But it's thought that it comes from those specific segments.

    04:32 So pre-ganglionic fibers pass from those segments via the lesser and least splanchnic nerves to the superior mesenteric ganglion.

    04:40 They synapse with the post-ganglionic fibers and then they run alongside the pre-ganglionic fibers of the vagus nerves via periarterial branches to the organs of the midgut.

    About the Lecture

    The lecture Foregut and Midgut – Autonomic Nerves of Abdominopelvic Organs by James Pickering, PhD is from the course Pelvis.

    Included Quiz Questions

    1. Celiac
    2. Superior mesenteric
    3. Inferior mesenteric
    4. Aortic
    5. Inferior hypogastric
    1. T5–T9
    2. T4–T7
    3. T3–T5
    4. L2–L4
    5. L3–L5
    1. Superior mesenteric
    2. Celiac
    3. Inferior mesenteric
    4. Aortic
    5. Lumbar

    Author of lecture Foregut and Midgut – Autonomic Nerves of Abdominopelvic Organs

     James Pickering, PhD

    James Pickering, PhD

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    Well organized and simple to understand
    By Deniz Y. on 11. June 2020 for Foregut and Midgut – Autonomic Nerves of Abdominopelvic Organs

    Very well explained lecture. Helped me finally understand the web of connections that is the ANS