 In this video we'll be clarifying some concepts of the lesser sack. Let's just get our bearings a little bit first. So we have the diaphragm here, cutting away these organs one by one for a better view. We have the liver, we have the stomach, we have the lesser omentum here, and we have the spleen down the back, a little bit of the kidney there as well. We also have the aorta and part of the inferior vena cava. So I've cut our model in this plane because I want to bring up an image that you may have seen before which is from an old version of Grey's Anatomy. And this shows us pretty neatly the boundary of the lesser sack. This blue bit here represents the peritoneum that bounds the lesser sack and all other peritoneum is in red. So let's draw that out on our own model. We see the entry involves the lesser omentum as the anterior wall, the peritoneum that covers the stomach and we encounter the gastro-lienal ligament which attaches to the spleen. We're going over the kidney because it's a retroperitoneal organ and the same for the aorta and the IVC. This opening here we'll address next, that's the epiploic foramen. This is in one plane the dimensions of the lesser sack. As you'll see further throughout this video, the lesser sack has quite bizarre dimensions so it can be really hard to visualize but hopefully this video will go some way to addressing that. Getting rid of that image now, I'm going to access the sagittal plane but the majority of the rest of this video. Before I do that, let's just have another look at the stomach with the lesser omentum attached. As you may know, the greater curvature of the stomach gives rise to the lesser omentum which originates in the liver. Let's bring in the rest of the liver to see a bit more of that. Take out that. Okay so the lesser omentum you can see here and remember that that forms the anterior border of the lesser sack. We're going to bring up another image which I imagine you'll be familiar with. Also from Grey's Anatomy, this cursed image. Let's move our sagittal plane in, cutting through the liver, the large bowel. And now we reach an important landmark regarding the epiploic foramen, that's the gallbladder. So once we've found the gallbladder we know we're not too far away because to the anatomical left of the gallbladder we'll soon find the entrance to the lesser sack. Moving on. Okay and now look at that. We have found the entrance to the lesser sack. I know that because one of the boundaries of the epiploic foramen is the IBC. When we encountered the IBC we know we've found the epiploic foramen. The other borders of the epiploic foramen are the first part of the duodenum, the free anterior portion of the lesser omentum, part of the liver and part of the IBC as well in this area. Okay and if we now have a little look around that should line up fairly well with where we define the entrance to the sack from the other angle. Alright so what I want to do now is keep moving this sagittal section back this way to the left and provide you with a couple more sagittal sections of the lesser sack to give you an idea of its dimensions throughout. We go up until the midline okay. So let's draw the boundaries of the lesser sack in the midline. Let's use the anterior border which is the lesser omentum as a starting point. We're going around the stomach because peritoneum imaginates organs in that way and then we're following the line of the greater omentum all the way down like this. Back up again to the posterior abs, I'm on a wall covering the retroperitoneal organs like the pancreas, up to the liver and back we go. We now have a look at that as well so it's a very different set of dimensions to the entrance. Let's move a bit further along with our sagittal plane now close to the end of the lesser omentum. Then following the lesser omentum going around the stomach down the greater omentum into the posterior abdominal wall, covering a little bit of the spleen, a little bit more of the stomach back to the lesser omentum and then we have another section. As I mentioned the dimensions of the lesser sack overall are quite bizarre but if you can piece together these sections in your mind we get a pretty good idea of how the space changes throughout the sagittal plane. We're going to leave it there. Thanks for sticking with us, I hope you enjoyed that. Make sure you hit subscribe and we will see you next time.