 Today we are going to discuss the esophagus, stomach, and alimentary tract. My name is Dr. Sanjay Sanyal, from his department chair. The structure that we see here is the thoracic part of the esophagus. The thoracic part of the esophagus extends from T1 to T10. The esophagus is in the posterior medial stymium and in this portion, the esophagus does not have any serosa. Therefore, here it is very prone to rupture and perforation, especially during foreign body removal by esophagoscopy, in which condition it can produce a very dangerous condition called medial stenitis. The esophagus is located just anterior to the azygous vein, thoracic duct, and it is located to the right of the thoracic aorta. As it descends down, it moves to the left, and it goes slightly anterior to the thoracic aorta. So this is about the thoracic part of the esophagus. It extends through the esophageal hiatus, which is at the level of T10, and after that it becomes the abdominal esophagus, and the abdominal portion of the esophagus is only half an inch long. It extends from T10 to T11 with a slight leftward tilt. Now we have shifted to the abdominal section, and my finger has gone into the esophageal hiatus, which is at the level of T10, and this opening is in the right crust of the diaphragm, which you can see here. So this small segment is the abdominal segment of the esophagus. The difference between this segment and the thoracic segment is that it is covered by visceral peritoneum, namely the cirrhosa, so therefore it gets a slight protection. And here I have made a small incision to show you that anterior vagus nerve is visible here, and this is the anterior vagus, which I have lifted up here, and likewise behind is the posterior vagus, which we cannot see. This is the external appearance of the gastroesophageal junction, and after that is the stomach. This is the cardio of the stomach. This is the cardial notch, the angle between the esophagus and the fundus of the stomach. This is the fundus of the stomach, which is in relation to the left home of the diaphragm. This is the greater curvature of the stomach, and this is the lesser curvature of the stomach. In the lesser curvature, this is called the incisura angularis, and this is the most dependent part of the lesser curvature. This portion of the stomach is the corpus of the body of the stomach, and it stops at the line drawn from the incisura angularis to the greater curvature, and after that this portion is the pyloric anterum, and after that is the pylorus, and then it goes to the diodenum. The diodenum has got four parts. This is the superior part, or D1. It is at the level of L1. Now this has got two subparts. The first inch of the first part is the intraperitoneal part, and it is within this structure here. This is the hepatodeodontal ligament, which has been removed, but the contents of the hepatodeodontal ligament are in place. So the portion opposite to that is the first inch of the first part. This is the part which is most known to diodenal ulcer. Then we have the remaining part of the superior part of the diodenum, that is at the level of L1. Then we have the descending part, which is from L1 to L3, and then we have the horizontal part, which is at the level of L3. And finally we have the fourth part, the D4, which goes from L3 to L2, before it merges with the diodenum. So these are the parts of the diodenum. This was the relationship of the hepatodeodontal ligament. My finger has gone into this space here. This is the epiploic foramen, or the foramen of Winslow. So structures in front of my finger are the structures which are in the hepatodeodontal ligament. The structures behind my hand are the posterior boundary of the foramen of Winslow, and they are composed of the inferior vena keva and the right supra-real gland. The structure above my finger is the liver, and the structure below my finger is the first inch of the first part of the diodenum. So these are the boundaries of the epiploic foramen, or the omental foramen of Winslow. And now my finger has gone into this space here. This space was covered by the lesser omentum, part of which has been preserved here. It was covered like this. So this has been reflected, and this space is the omental bursa or the lesser sac, which extends not only behind the lesser omentum, but it also goes behind the stomach. And these structures that we see here, these are all the structures in the bed of the stomach. We see the pancreas, left kidney, left supra-real, left dome of diaphragm, splinic vessels, which are running on the upper border of the pancreas and behind the pancreas. And of course the transverse mesocolon, which we cannot see here. These are the structures which form the bed of the stomach, which allows the stomach to move when it mixes the food. Coming to the relations of the diodenum. This is the descending part of the diodenum, which is in front of the left kidney and the left supra-real. Coming to the horizontal part of the diodenum, we can see that it is crossed by superior mesentric artery and the superior mesentric vein. This is a place where the diodenum can potentially get compressed by the superior mesentric artery. And finally, this is the fourth part of the diodenum, d4, and this is the jigenum. And my finger is located, this is the dj flexure. Extending from the dj flexure, going behind the pancreas, will be the suspensory ligament of diodenum, also known as the ligament of trites. And just by the side of the dj flexure, we see a diperitoneal depression. This is called the paradeodinal fossa. And this is a potential site of internal herniation. And when we are trying to remove a trapped loop of intestine from here, we may have difficulty because running in the free margin of the paradeodinal fossa, we have a very important vein. And this vein is the inferior mesentric vein. Now I'm going to open out all these intestinal contents. We will show the interior. Now we have opened up the abdominal part of the esophagus. And this is where I had showed you the fibres of the anterior vagus. When we look at the mucosal pattern here, we cannot see very clearly in the cadaver, but in a living specimen, we will be able to see a wavy line, which is called the z-line. And that z-line marks the junction between the stratified squamous epithelium of these of vagus and the cholerna epithelium of the stomach. But in this case, in the cadaver, we may not be able to see it. These folds of the gastric mucosa, called the gastric rugae, this is to increase the surface area. And when I put my finger in, my finger has gone into the fundus of the stomach here. This gastric rugae occupies the fundus and the body of the stomach. And as we keep going, we will open out the entire stomach and you can see the gastric rugae here. If we were to look along the lesser curvature of the stomach, we notice that the gastric rugae are linear, parallel, and more regular in nature. That portion of the interior of the stomach is called the gastric canal. Or in German it is called the magenstrasse. This is the root by which liquids go directly into the diurnum. Now we come to the region of the pyloric entrum and the pylorus. And this is the region of the pylorus, where the sphincter is located. And if you look at the cut margins, you will notice that the muscle is very thick here. Especially thick at this portion here and this portion here. So this is the region of the pyloric entrum, and this is the region of the pyloric sphincter. And this is the true pyloric sphincter, which controls gastric emptying. And after that, we come to the first part of the diurnum that is D1. This part of diurnum, again, the mucosal pattern is very closely similar to the stomach. That is, it is longitudinal and linear. But as we go further down, we notice that the mucosal pattern has changed. The mucosal pattern in the subsequent part of the diurnum is transverse. So this is the descending part of the diurnum. And here I would like to draw your attention to a very important structure. And that is this one where my probe has gone in. This is major diurnal papilla, which is the opening of the main hepato-pandemic duct of Virso. In this region, if you look closely, you will find that there is a specific arrangement of the mucosa. Just above the hepato-diurnal papilla, we have a fold of mucosa above that. And this is called the mucosal hood. And below that is a longitudinal fold of mucosa. This is an important landmark for the endoscopist when he wants to calculate the hepato-pandemic ampulla. And by using this landmark, he locates the position of the major diurnal papilla. So this is also the junction between the foregut and the midgut. So these are the structures which we see in the interior of the diurnal. Thank you very much for watching, ladies and gentlemen. Dr. Sanjeev Sanyal signing out. If you have any questions or comments, put them in the comment section below. Thank you for watching. Like this video and subscribe.