Video: Arteries of the pancreas, duodenum and spleen
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Hey everyone! This is Nicole from Kenhub, and welcome to our tutorial on the arteries of the pancreas, duodenum, and spleen. In this video, we're going to be exploring the pathways in which oxygena... Read more
Hey everyone! This is Nicole from Kenhub, and welcome to our tutorial on the arteries of the pancreas, duodenum, and spleen. In this video, we're going to be exploring the pathways in which oxygenated blood travels to reach and supply these organs. First, we're going to do a quick review of the main parts of these organs and how they are related to each other and other structures in situ. Then, we'll dive into the arteries and discover how these organs receive their blood supply.
When looking at the organs, we'll begin with the spleen, then look at the duodenum and its four parts as well as some internal features. We’ll then move on to the pancreas and identify its main parts as well. When we move on to the blood supply, we'll begin with the arterial supply to the spleen, move on to the celiac trunk, and see how it contributes to supply all three of these organs through its various branches. We’ll then check out the superior mesenteric artery and see how it contributes to supplying some of these organs, and to wrap up, we'll put these arteries we've identified together to really understand the arterial supply to the duodenum. And, finally, we'll look at the arterial supply to the pancreas.
In this image, we're looking at the abdominal cavity from an anterior view. The liver with its left and right lobes is being retracted superiorly. The stomach has been cut away and we can see the proximal edge cut here and the distal edge cut here where it meets the duodenum. This leaves us with a nice clear view of the organs we're interested in – the spleen, the duodenum, and the pancreas. Let’s begin with the spleen.
The spleen is the largest immunological organ in the body. We can see it here highlighted in green. It lies within the peritoneum on the upper left side of the abdomen between the ninth and the twelfth ribs. We could also call this area the left hypochondriac region of the abdomen. Anterior to the spleen is the stomach, which has been cut away in this image. Posteriorly and laterally is the convexity of the diaphragm. On the medial aspect of the spleen and, what we can see here, is the tail of the pancreas close to the hilum of the spleen.
The duodenum which is highlighted in this image is the first part of the small intestine followed by the jejunum and the ileum. Food passes through the pyloric sphincter of the stomach to enter the duodenum for further digestion. The duodenum can be broken down into four parts. The first part, highlighted here in green, is known as the superior part; the second, highlighted now, is known as the descending part of the duodenum; the third part just here is known as the horizontal part; and, finally, the fourth part is known as the ascending part of the duodenum.
Now let's look a little bit more closely at the descending part of the duodenum. Within the second or descending part of the duodenum are the openings for the secretion of digestive enzymes into the duodenum from both the pancreas and the liver. In this image, we're looking more closely at the duodenum. The superior and descending parts have been opened to show the internal features.
The smaller opening seen here is called the minor duodenal papilla and allows the accessory pancreatic duct to open into the duodenum. The larger and more distal opening seen here is the major duodenal papilla. The major duodenal papilla is the opening for the common bile duct and the main pancreatic duct to empty into the duodenum. We’ll see later on that the major duodenal papilla serves as a landmark for the change in arterial supply to the duodenum.
Finally, we'll have a look at the pancreas. The pancreas is a unique abdominal organ that is classified as both endocrine and exocrine in function. It is situated posterior to the stomach in the retroperitoneal space except for its tail which communicates with the medial aspect of the spleen. Macroscopically, we can divide the pancreas into four of main parts. From right to the left side of the body, these parts are the head, the neck, the body, and the tail.
The head lies within a C-shaped curvature of the duodenum, as you can see here, and it is the widest, broadest part of the pancreas. Here we can see the neck of the pancreas which is the part of the organ that is situated between the head and the body of the pancreas. The body of the pancreas which we can now see is the part that travels transversely towards the left side of the body. And, finally, here's the tail, which is the left tip of the pancreas.
As you may remember from your embryology courses, the primitive gut tube can be divided into three regions, namely the foregut, the midgut, and the hindgut. These divisions relate directly to the arterial supply that they each receive. There are three unpaired arteries that arise from the anterior surface of the abdominal aorta – part of which we can see here highlighted in green.
In this new image, we can see the entire length of the abdominal aorta. It begins as it enters the abdomen posterior to the diaphragm and ends inferiorly when it bifurcates into the right and left common iliac arteries. The first unpaired artery arising from the abdominal aorta is the celiac trunk. We can see the celiac trunk and its branches here. The branches of the celiac trunk supply structures belonging to the foregut.
The second unpaired artery is this one here. This is the superior mesenteric artery which supplies structures belonging to the midgut. And, finally, the third unpaired artery is this one here. This is called the inferior mesenteric artery and it supply structures that are part of the hindgut.
The organs we're focusing on today are mostly part of the foregut, the exception being the distal duodenum and the inferior part of the head of the pancreas. The foregut begins with the abdominal part of the esophagus and ends at the level of the major duodenal papilla at the midpoint of the descending part of the duodenum. Therefore, the foregut includes the abdominal esophagus, the stomach, the duodenum proximal to the major papilla, the liver, the pancreas, and the gallbladder. The spleen, although it is not part of the gut tube, is directly related to the foregut.
Since in this tutorial we're focusing on organs belonging to the foregut and a small portion to the midgut, we’ll find that the arteries supplying these organs arise mostly from the celiac trunk with lesser contribution from the superior mesenteric artery. Let’s start with the spleen.
The blood supply to the spleen is perhaps the most straightforward. It simply receives blood along one artery called the splenic artery which we can see in this image highlighted in green. In this image, the stomach has been cut away so the splenic artery is actually running posterior to the stomach. The splenic artery is a very torturous artery that runs along the posterior abdominal wall and along the superior aspect of the pancreas. The splenic artery is one of the three main branches arising directly from the celiac trunk.
So there we go – arteries of the spleen done.
Now, let's take a closer look at the celiac trunk. The celiac trunk arises from the anterior surface of the abdominal aorta at the level of vertebral body T12. Along with the splenic artery, it also gives rise to the common hepatic artery and the left gastric artery. The left gastric artery which we can see here, as its name suggests, supplies the left part of the lesser curvature of the stomach. We won't follow that today though as the stomach isn't our main focus.
The common hepatic artery, however, will give rise to some arteries that we're interested in. These arteries will supply parts of the pancreas and the duodenum. As its name suggests, the common hepatic artery will also head towards the liver as the main arterial supply there. Let’s look at the details of this artery a little more closely.
The common hepatic artery usually splits into three arteries, and I say usually because the branching pattern can be a bit variable in this area. One that we won't really pay attention to is the hepatic artery proper. This is the artery that we can see here travelling towards the liver and the gallbladder. The second one that we won't really look at this time is the right gastric artery which we can see here. Similar to the left gastric artery, it supplies the lesser curvature of the stomach but, of course, on the right side.
The third artery is the one we'll pay special attention to for this tutorial which is the gastroduodenal artery. The gastroduodenal artery which is highlighted now in green will give rise to branches that supply parts of the stomach, duodenum, and pancreas. The main branch to the stomach is the right gastroomental artery running along the right aspect of the greater curvature of the stomach. This is the cut artery we can see here. The remaining branches from the gastroduodenal artery are going to contribute to the blood supply of the duodenum and the pancreas.
Firstly, the structure highlighted here in green is the supraduodenal artery. The supraduodenal artery supplies the first part of the duodenum. Next, we can see the gastroduodenal artery giving off two branches called the anterior superior pancreaticoduodenal artery which we can see in the image on the left and the posterior superior pancreaticoduodenal artery which is highlighted in the image on the right. The anterior superior pancreaticoduodenal artery supplies the anterior superior aspects of the pancreas and the duodenum. The posterior superior pancreaticoduodenal artery supplies the posterior superior aspect of the pancreas and the duodenum.
Let’s break down the names of these arteries. So, the terms anterior or posterior will supply the anterior or posterior aspects of the relevant organs. Superior means that it will supply the superior aspects of these organs, ‘pancreatico’ means that it supplies the pancreas, and ‘duodenal’ means supplying the duodenum. Great! These are some key arteries that we're looking for today. The names of these arteries are both quite a mouthful, but if you look at each part of their name, it states exactly where it is and what it's supplying.
The anterior superior pancreaticoduodenal artery supplies the anterior superior aspects of the pancreas and the duodenum. The posterior superior pancreaticoduodenal artery supplies the posterior superior aspects of the pancreas and the duodenum. Easy, right?
Both superior pancreaticoduodenal arteries run along the head of the pancreas from superior to inferior. Along their course, they both give off branches that run transversely back to the duodenum as we can see on this image here. This shows that the superior pancreaticoduodenal arteries do in fact supply both the head of the pancreas and the duodenum. Now usually when we have a superior structure, we have an inferior one as well, and this is in fact the case for the pancreaticoduodenal arteries.
The superior pancreaticoduodenal arteries, which are both highlighted in this image, will anastomose inferiorly with the inferior pancreaticoduodenal arteries – again, both an anterior and posterior branch of each. The inferior pancreaticoduodenal arteries arise directly from the superior mesenteric artery. Remember, the superior mesenteric artery supplies structures in the midgut so it will be supplying the portion of the duodenum distal to the major duodenal papilla as well as the inferior part of the head of the pancreas. Let’s look at these arteries a little more closely.
In this image, we can see the superior mesenteric artery highlighted in green. In this image, the pancreas has been removed and we can see the highlighted superior mesenteric artery arising posterior to where the pancreas was from the anterior surface of the abdominal aorta at vertebral level L1. Let’s switch back now to the image with the pancreas intact though and look at the first branch that arises from the superior mesenteric artery – the inferior pancreaticoduodenal artery.
The inferior pancreaticoduodenal artery bifurcates into an anterior and a posterior branch forming the anterior inferior pancreaticoduodenal artery which we can see in the image on the left and the posterior inferior pancreaticoduodenal artery which is highlighted on the image on the right. These arteries will run the head of the pancreas giving off branches to the duodenum, a couple of which we can see here. At the level of the major duodenal papilla, they will anastomose with their superior counterparts.
Now that we've identified these arteries and we found all the arteries that supply the duodenum, let's put it all together.
Firstly, the supraduodenal artery supplies the first or the superior part of the duodenum. Next, the anterior and posterior superior pancreaticoduodenal arteries supply the proximal part of the duodenum until the level of the major duodenal papilla which is in the second or descending part of the duodenum. At the level of the major duodenal papilla, the anterior and the posterior superior pancreaticoduodenal arteries anastomose with the anterior and posterior inferior pancreaticoduodenal arteries and these inferior arteries will supply the remaining distal portion of the duodenum.
If we trace these arteries back to their origins off the abdominal aorta, the blood supply to the proximal duodenum up until the major duodenal papilla, is from the celiac trunk where distal to that, the blood supply comes from the superior mesenteric artery.
So now we've covered the arteries of the spleen and the duodenum and we started on the pancreas. Let’s remember what we've learned about the pancreatic blood supply so far and then add it to complete the picture. Yet, again, the pancreaticoduodenal arteries come into play. All four of these arteries listed here will supply the head and the uncinate process of the pancreas. To find the blood supply of the neck, the body, and tail of the pancreas, we need to revisit the splenic artery.
Remember the splenic artery which arises from the celiac trunk? We can see it highlighted in this image in green. It courses along the superior aspects of the pancreas from the celiac trunk to the spleen. Along the way, it gives off up to ten branches that will supply the neck, body, and tail of the pancreas which is just what we're looking for. A couple of these arteries are highlighted in this image, and as you can see, some of these branches form anastomosis with each other here and with branches from the pancreaticoduodenal arteries in the head of the pancreas as we can see here.
Speaking of that splenic artery, we’ll now look at a clinical correlate of that artery.
Aneurysms are bulges or outpockets in the walls of blood vessels, usually where a blood vessel wall is weak. Splenic artery aneurysms are the most common aneurysms of the visceral arteries although they're not hugely prevalent. Most of these aneurysms are asymptomatic and do not rupture. However, when they do rupture, there is a relatively high mortality rate. The splenic artery, as we discussed, carries a large amount of blood to important organs including the spleen and the pancreas.
If a splenic artery aneurysm ruptures, massive internal hemorrhaging occurs which can result in death, if not caught and treated immediately. Due to this, patients with a splenic artery aneurysm who have additional risk factors for a rupture can be treated using a technique called coil embolisation. This is where the aneurysm is filled with a certain material to help reduce the risk of rupture.
So now you're an expert on the arteries of the spleen, the duodenum, and the pancreas. But let's have a quick review to summarize what we talked about today.
We first looked at the arterial supply to the spleen and found the splenic artery – the largest branch arising from the celiac trunk. Next, we found the blood supply to the duodenum coming from both the celiac trunk and the superior mesenteric artery – the division between the two being at the major duodenal papilla. The blood from the celiac trunk travels to the duodenum along the following path – the celiac trunk to the common hepatic artery to the gastroduodenal artery.
From the gastroduodenal artery, three arteries arise to supply the duodenum – the supraduodenal artery, the anterior superior pancreaticoduodenal artery, and the posterior superior pancreaticoduodenal artery. The last two will anastomose with the anterior inferior pancreaticoduodenal artery and the posterior inferior pancreaticoduodenal artery respectively at the level of the major duodenal papilla. These inferior pancreaticoduodenal arteries arise from the superior mesenteric artery.
Finally, we looked at the arteries supplying the pancreas and, keeping our eyes on the pancreaticoduodenal arteries which travel along the head of the pancreas, we then revisited the splenic artery to find the arteries that supply the neck, the body, and the tail of the pancreas. Arising from the splenic artery are up to ten branches dividing into the pancreas – two of which we can see highlighted on this image. Some of these arteries formed anastomosis with each other and with the pancreaticoduodenal arteries. And just like the duodenum, the pancreas receives blood from both the celiac trunk and the superior mesenteric artery.
That brings us to the end of our tutorial on the arteries of the pancreas, the duodenum, and the spleen. I hope you enjoyed it. Thanks for joining me!