- 7/5/2025
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00:00Hello everyone, this is João from CanHub and welcome to another anatomy tutorial where this
00:05time we're going to be talking about the stomach in situ. So what we're going to be doing here on
00:11this tutorial is mainly exploring this image that you see now on the screen which shows the anterior
00:18view of the abdomen. If we were to then cut all the muscles of the interior wall, so the interior
00:25trunk wall muscles are all removed here and a few other structures to then expose the stomach here.
00:32You can see that we're just moving back the liver so we can then show a bit more or expose the stomach.
00:40You can also see here a bit of the colon or the large intestine, the gallbladder, and a few other
00:47structures that we're going to be talking about here. So we're going to look at all these structures
00:52that are found nearby the stomach. As you probably know, the stomach is the most dilated part of the
01:04gastrointestinal tract and takes on a short J shape. You can also see a bit of the stomach here on this
01:13image, highlighted in green. Now the stomach is positioned between the esophagus, which you see
01:20here on this image, and also the small intestine. The stomach is found in the epigastric umbilical
01:29and left hypochondriac regions of the abdomen. Now it can be subdivided into four parts, the cardiac part,
01:39the fundus, the gastric body, and also the pyloric part, which we will be looking at on the next slides.
01:47In this tutorial, we will not be going into great detail about histology of the stomach mucosa.
01:55However, I would like to mention that though there are four divisions of the stomach, only three are
02:02histological distinct. I would like to also give you a quick overview of the types of glands that are
02:08found on the lamina propria of the stomach, and they are first the alkaline mucus-producing mucus
02:16neck cells. Now this alkaline mucus protects the epithelium from self-digestion through gastric juices.
02:26Hydrogen and chloride ion-secreting parietal cells. The hydrogen and chloride ions bound to then form
02:34hydrogen chloride, or HCl, that keeps the pH level of the stomach around 1 to 1.5.
02:43Pepsinogen and gastric lipase secreting chief cells. Pepsinogen, the inactive precursor of
02:51pepsin enzyme. There are also enteroendocrine cells. These cells secrete the hormones histamine,
03:00serotonin, cholecystokinin, somatostatin, gastrin, and endorphins.
03:08Now that we had a quick glance on the histology of the stomach, we're going to start talking about
03:14the parts. Starting with this one that you see here highlighted in green, this is the cardiac part
03:19of the stomach. Notice here, this is the highlight, the cardiac part of the stomach.
03:25Now this is a portion of the stomach near the lower esophageal sphincter, where the contents from the
03:33esophagus are emptied into the stomach. And at its terminal end, the esophagus joins the cardiac part
03:41of the stomach, forming then the esophageal stomach junction. In this specific part of the gastrointestinal
03:47tract, the stratified squamous epithelium of the esophagus abruptly changes into the simple
03:55columnar mucus secreting epithelium of the cardiac part of the stomach. The next structure we're going
04:03to be highlighting here is known as the fundus. This is the cranially located dome-like part formed by the
04:11upper curvature of the stomach. It lies in the left hypochondriac region of the abdomen, just beneath the
04:18diaphragm, which you see a little bit here on this image. Notice the diaphragm. This part is usually filled with air
04:26and is separated by the cardia by the cardiac incisura, which is also known as the cardiac notch. The next structure
04:36we're going to be highlighting is known as next part of the stomach to be more specific, the gastric body,
04:42or the body of the stomach. Now this is the largest part of this organ. It forms the lesser curvature
04:50cranially, which you can see here. This is the lesser curvature of the stomach, and also forms then
04:57the greater curvature, caudally. Now this central portion of the stomach is located between the cardia,
05:05or fundus, and the pyloric part. The next part of the stomach we're going to be highlighting is then
05:12known as the pyloric part. It's located just after or below the gastric body. This distal segment of
05:20stomach lined with mucosa that contains mucus secreting cells or mucus neck cells and enteroendocrine
05:29cells. The next structure we're going to be highlighting now that you see here is the
05:35pylorus. The pylorus sphincter marks the lower end of the stomach and the entrance to the duodenum,
05:42which you see a little bit here, the duodenum. It is the most distal part of the stomach. It is marked
05:49on the surface by the pyloric constriction that contains a thickened ring of gastric circular muscle
05:57known as the pyloric sphincter. The next structure I would like to highlight here, one that I mentioned
06:04before, this is known as the greater curvature of the stomach. This is a large, convex curvature of
06:11the stomach directed right and downward and is about four to five times longer than the lesser
06:18curvature. So as you can see, it starts at the cardiac notch of the cardiac orifice and then goes
06:24all the way to end at the pyloric part of the stomach. In terms of blood supply, the short gastric
06:34arteries, also gastric branches of the left gastroepiploic artery and gastric branches of the right
06:41gastroepiploic artery provide then blood supply to the greater curvature of the stomach. Now please note that
06:49you may also come across the left and right gastroemental arteries being referred to as
06:54the gastroepiploic artery. Now these terms are used interchangeably. The next structure we're going to
07:01be highlighting, we mentioned before, this is then the lesser curvature of the stomach, which is a small
07:06curvature of this organ going from the cardia to the pyloric orifice that is then directed to
07:13the right and also downwards. Provides attachment for the hepatogastric ligament and receives blood
07:24supply from both the left and right gastric arteries. The next structure we're going to be highlighting
07:31here is known as the duodenum. Now this is a continuation of the stomach and the duodenum is a
07:38C-shaped loop that makes the initial portion of the small intestine. Now this structure is located
07:47adjacent to the head of the pancreas and is retroperitoneal except for the first part. Now this
07:55section of the small intestine connects to the stomach and the jejunum. The jejunum is also another
08:02continuation of the small intestine and the duodenum is comprised of four anatomical parts. The superior
08:11part, which is the horizontal first part of the duodenum, is known as the ampolla or duodenal cap
08:20and most duodenal ulcers occur in this part of the duodenum. Just a reminder of a few things you need to
08:27know whenever we talk about the parts of the duodenum. The other part of the duodenum is known as the
08:34descending part. So the lateral descending part that starts at the superior duodenal flexure and ends at
08:41the inferior duodenal flexure. This part of the duodenum contains the major duodenal papilla, which you can
08:49see here highlighted in green. This structure is the opening for the pancreatic duct. There is also a
08:57horizontal part. This horizontal segment is located below the head of the pancreas and begins at
09:03the inferior duodenal flexure and passes in front of the inferior vena cava, the abdominal aorta,
09:10and also the vertebral column. And finally, where you can find also on the duodenum, the ascending part
09:17that is located to the left of the head of the pancreas, and this part passes upwards up to the
09:24duodenal jejunal flexure. Now, to have a better view and understanding of all these parts, I suggest
09:30you look at another tutorial we have here at KenHub, where we explore the duodenum in greater detail.
09:37Now, the duodenum receives partially digested food from the stomach and plays a vital role in the chemical
09:44digestion of food in preparation for absorption in the small intestine. Now, the duodenum contains
09:52mucous-secreting glands, called the bruners, glands, and these are found only in the duodenum.
10:00It is supplied by the superior pancreaticoduodenal artery, a branch of the gastroduodenal artery,
10:07and also supplied by the inferior pancreaticoduodenal artery, which is a branch of the superior
10:15mesenteric artery. Just a few reminders of the blood supply of the duodenum. We're now ready to
10:22move on to another structure that we see here, clearly now highlighted in green. This is known
10:27as the greater omentum. The greater omentum is a double-layered, apron-like fold of peritoneum that
10:35is fixed to the greater curvature of the stomach, hanging down and also reflecting back on itself,
10:41to then ascend to attach inferiorly to the transverse colon. The greater omentum contains
10:49variable amounts of fat and contributes to immunity owing to its macrophage collection.
10:56In addition, it is known that the greater omentum isolates wounds and infections in the peritoneal cavity.
11:04Vascular supply to the greater omentum comes from the left and right gastroepiploic arteries,
11:13which are branches from the celiac trunk. If there is a greater omentum, there should be
11:20then a lesser one, the lesser omentum. This one is also a double-layer peritoneal sheet
11:27that extends from the liver to the lesser curvature of the stomach. And you can clearly see here
11:33on this image, how it extends from the liver here, all the way to the lesser curvature of the stomach.
11:39Just a reminder here that the omental foramen, which we will see in the next slide,
11:44is found at the right border of the lesser omentum. This double-layer of peritoneum also
11:50will be transmitting various structures, including lymphatics, portal vein, hepatic artery,
11:58left gastric artery, and gastric veins, as well as the common bile duct and hepatic plexus.
12:08Next, we're going to be seeing then one of the structures I mentioned before, now highlighted
12:12in green notice here. This is then the omental foramen. So at the right border of the lesser omentum,
12:20the two layers are continuous and form a free margin, which constitutes the interior border
12:29of the omental foramen. Now the omental foramen, also known as the epiploic foramen or foramen of
12:36Winslow, is found between the greater sac of the abdomen and the omental bursa, also known as
12:44the lesser sac. Now this foramen is an opening or a passage of communication that borders the lesser
12:52omentum, the peritoneal coverings of the inferior vena cava, the caudal lobe of the liver, and the
13:00first part of the duodenum, and also the gastrointestinal and splenorenal ligaments. Next, I would like to
13:08highlight one structure that I mentioned here so you can have a bit of understanding of what is
13:13happening around the stomach. This highlighted structure is the diaphragm, and as I mentioned
13:18before, the fundus of the stomach is located beneath the thoracic diaphragm, and in this illustration you
13:26can see a small portion of this skeletal muscle sheet in relation to the stomach. Now the esophagus
13:33descends into the abdominal cavity through this orifice, I would say, or this hole in the diaphragm,
13:43which is known as the esophageal hiatus, to then attach to the cardia of the stomach. The next thing
13:51I would like to highlight here on this image, which you see here, is the parietal peritoneum.
13:57Very close to the diaphragm, as you can see in the peritoneal cavity, we see then the parietal
14:03peritoneum. Now the parietal peritoneum is one of the two mesothelial layers that make up the peritoneum.
14:12The other layer being the visceral peritoneum. These two layers are inseparable. Parietal peritoneum
14:21covers the internal abdominal walls and is supplied by the regional vasculature, whereas the visceral
14:28peritoneum encapsulates the individual abdominal organs. The next structure we're going to be
14:34highlighting here that you see is, this is clearly the right lobe of the liver. One of the structures
14:41of the abdomen that borders the stomach is the right lobe of the liver, which you see here.
14:47It's separated from the left lobe of the liver by the falciform ligament, which we will talk about
14:53later on in this tutorial, and also by the ligamentum venosum posteriorly, which is continuous
15:00with the round ligament of the liver caudally. You can also see here then the left lobe of the liver.
15:10So this is the smaller left lobe of the liver, which is here bordering the superior part of the stomach
15:16near the fundus. It is located in the epigastric and hypochondriac regions, and the left lobe
15:23is separated from the right lobe by the falciform venosum and round ligaments of the liver.
15:33I'd like to show a couple of these ligaments. One of them that you can see here, this is the round
15:38ligament of the liver, which we just saw that the left and right lobes of the liver are separated
15:45on their visceral surface by the round ligament of the liver. This ligament is a remnant of the
15:52fetal umbilical vein, and it divides the left part of the liver into medial and lateral sections.
16:01It exits in the free edge of the falciform ligament and inserts around the umbilicus. Speaking of which,
16:09we're going to also show you here this ligament, which is then the falciform ligament.
16:14Notice here on this image below, we have the interior view of the liver as we were to remove
16:21all these tools and just have the liver resting then on top of some of these structures, but now
16:30seen from an interior view. The other ligament that is then visible here, highlighted in green,
16:36is the falciform ligament of the liver that extends from the upper part or the upper convict surface
16:44of the liver to the diaphragm and the interior abdominal wall, allowing then the liver to be
16:50attached to the interior abdominal wall. Another structure you can see here, now this green structure
16:57that we just changed the highlight here, this is the gallbladder. This is another structure closely
17:03located to the stomach and the gallbladder serves as a reservoir for bile produced by the liver and is
17:10then comprised of a fundus body and neck, which we will look into on a separate tutorial, but just give
17:16you an idea of the structures that you find or the structure of the gallbladder. Now this pear-shaped
17:23organ receives blood supply from the cystic artery and receives sympathetic innervation from the celiac
17:31plexus, parasympathetic innervation from then the 10th cranial nerve, the vagus nerve, and also sensory
17:40innervation from the right phrenic nerve. One structure you can see here on this image as well is known as
17:48the ascending colon, and we have here just a bit of the large intestine on this image, but I wanted to show
17:54you the large intestine here completely so you can see that this is the ascending colon which is the
18:02part that we see here of this image of the stomach in situ. So this is the part of the large intestine
18:09that ascends retroperitoneally on the right side. It is the section of the large intestine between the
18:16cecum, which is located inferior to it, and the transverse colon superiorly. So as a reminder here,
18:24the part between the cecum and the transverse colon, which is this portion. Now it receives sympathetic
18:32innervation from the thoracic splanchnic nerves and parasympathetic innervation from the vagus nerve.
18:39You can also see a little bit here now of the transverse colon. So immediately after the ascending
18:46colon, we see this part of the large intestine. Now the transverse colon is the part of the large
18:53intestine between the right colic flexure and the left colic flexure. To be more specific,
18:59this is the right colic flexure and this is the left one. This transverse segment is the most movable
19:07part of the colon and is located intraperitoneally. Here we can see a small portion of the transverse
19:15colon on this image of the stomach in situ. The transverse colon receives blood supply from the
19:22middle colic artery, a branch of the superior mesenteric artery. If we look here also on this
19:30image of the stomach in situ, we see this structure, a little bit of this structure here, just to show
19:38you that we have a kidney. To be more specific, the right kidney here. So posterior to the right colic
19:45flexure, we see this small part of a very important organ, which is then the right kidney. The kidneys,
19:52as you know, they play a very important role in the urinary system. Now they are bean-shaped organs,
20:00the very famous bean-shaped organs that are responsible for the removal of the byproducts of metabolism.
20:08The kidneys are located on the posterior wall of your abdomen in the retroperitoneal space.
20:15The right kidney is located slightly lower than the left kidney, due to the position of the liver in the
20:21abdominal cavity. And in this illustration, you can see a portion of the right kidney in relation to
20:27the stomach. And here on this image, if I remove the stomach, the liver, you can see then the right
20:35kidney here, highlighted in green, and also the left one. Finally, here on back to this image of the
20:44stomach in situ, we find this structure highlighted in green, which is a very important one, the spleen.
20:52Found in the left side of the peritoneal cavity, we see then this organ. Now the spleen is the
20:59largest immunological organ of the body. Here you can see a portion of the spleen in relation to the
21:05stomach. It is located intraperitoneally inferior to the diaphragm on the left side of your abdomen.
21:13And if I remove here the stomach, you can then see the spleen highlighted in green on the left side of
21:22your abdomen. The main functions of the spleen include immune responses involved in immune responses,
21:30also synthesis of antibodies, filtration of blood, also lymphopoiesis, phagocytosis.
21:48And that's the key.
21:54So
21:58it's
21:58so
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