Variations in the Portal System

00:01 So now let's have a look at the formation of the portal vein in more detail.

00:05 Now we know where these main branches are coming from.

00:08 We can actually see some variation in the formation of the portal vein.

00:13 This would be the most classic example and one you'd see in many textbooks.

00:17 But you'll also see these variations as well as they're often well described.

00:21 But this is the classic one.

00:23 Hepatic portal vein is going to receive the left gastric directly.

00:27 The formation of the portal vein is really going to be the merging of the splenic vein and the superior mesenteric vein.

00:35 So the union of those two veins together is going to form the hepatic portal vein with the left gastric running indirectly to that portal vein, That covers most of the foregut and the midgut.

00:48 The hindgut drains into the inferior mesenteric vein.

00:51 And this often runs up and ascends towards the splenic vein where it unites with the splenic vein, typically underneath the neck or the body of the pancreas.

01:01 Here we've drained all of the foreguts, the midgut, and the hindgut.

01:05 But as I said, there is some variation.

01:08 Sometimes the left gastric vein can simply drain into the splenic vein without draining into the hepatic portal vein once it's formed.

01:15 It doesn't particularly make any difference.

01:17 It's just a slight variation.

01:20 The same time the inferior mesenteric vein, instead of draining into the splenic can drain into the superior mesenteric vein directly.

01:28 And if that's happening, maybe we have a version with the left gastric goes back into the portal system.

01:34 So you can see just by a couple of slight variations.

01:37 You have three different versions there.

01:40 And here we can see those different versions and how they can all be arranged within the portal system.

01:46 It doesn't particularly matter about these variations.

01:49 It's good to be aware that variations can occur.

01:52 But let's not get too bogged down and remember things specifically.

01:55 Let's understand the classic version and appreciate some variations may also occur.