What's up? Medite here. Let's talk about the spleen, which is a part of the lymphatic system. What we're gonna do today is firstly cover the external structures of the spleen.
Then we're going to go through the basic functions and the topography. And then we're gonna look at the coverings and the ligaments around the spleen. So let's start with the external structures.
The Latin name for the spleen is Lien and is located on the left side of the abdominal cavity. So it's in the complete opposite side of the liver. Let's now take the spleen out to focus on the external structures of it.
The spleen is about 12-14 cm long, 8-10 cm wide, and 3-4 cm thick. So the spleen, in contrast to all other organs in the abdominal cavity, is very small. Much smaller than other organs.
And it weights around 140-200 grams. So it's quite heavy compared to its size. And the reason why it's so heavy is because it contains a lot of blood.
And that really reflects its function. There are two major functions the spleen has that I'm going to mention in this video that is essential to know regarding the spleen. And the first one is its ability to destroy old red blood cells. Now if you look at the spleen, the spleen of course has its own blood supply. So blood is going to move into the spleen through the splenic artery.
of course that artery is going to divide many many times and supply many different structures within the spleen. And then of course it's going to be drained by the splenic vein. Now the reason why I mention this is that even though the spleen is a part of the lymphatic system, the spleen does not actually filter lymph like lymph nodes do. Notice that there's actually blood coming into the spleen.
And so the spleen, even though it's classified as a secondary lymphatic organ, is going to be monitoring blood, not lymph. Lymph node monitors lymph. And here, just to remind you of how the lymph node filters lymph, remember the interstitial fluid is in the space between the cells and the blood vessels.
So lymph vessels drain interstitial fluid into lymph nodes, which is what we call lymph. So lymph nodes will then monitor the lymph for any type of microorganisms and then dump the lymph into the blood vessels again. So lymph nodes monitor lymph. The spleen is gonna monitor blood, and it's gonna monitor it for two things. The first function of the spleen is to destroy old red blood cells.
So the spleen is usually referred to as the graveyard of red blood cells. So when blood moves in through the splenic artery, it's bringing with it red blood cells but also platelets. And so if red blood cells are damaged and they're not serving their function, or platelets the same thing, not serving their function, the spleen is going to be able to detect that and destroy those red blood cells and the old platelets. So it's able to monitor the blood, not lymph, because it has its own blood supply.
So I hope that made sense. The other thing the spleen is going to do is that it can actually mount an immune response against foreign matter in the blood. So there's always a chance, always a chance that you can have pathogens in the blood.
That's never a good thing, called bacteremia if the pathogen is bacteria. But if you have pathogens or foreign matter of any kind in the blood, then that material is eventually gonna make its way into the spleen. And so you would want, theoretically, to mount an immune response against it. And so the spleen is gonna be very similar to the lymph node, because the lymph node also activates an immune response but through lymph, not blood.
So that is the function of the spleen. Alright, so if we look at the abdominal cavity anteriorly, you will see that the spleen lies in the left hypochondriac region. The spleen has two surfaces.
It has the diaphragmatic surface, which faces the perfectly drawn diaphragm here. And it also has the visceral surface, close to the stomach, the pancreas, and even the left kidney and the transverse colon. On the visceral surface, you'll find an important structure called the splenic helium, which is the entrance and exit of blood vessels and nerves.
Now the spleen is protected, it's covered by two types of coats. The first one is the fibrous capsule, which is a fibrous layer that surrounds the spleen. Around the capsule, there's a tunico serosa, which is a slippery surface that is formed by the different peritoneal ligaments. And so if you add the perfectly drawn diaphragm again, the first peritoneal ligament you will see is the gastrosplenic ligament.
That is the ligament that connects the stomach to the spleen. It also connects to the diaphragm through the phrenicosplenic ligament. That's kind of a hard name, but remember phrenic Spleenic is everything to do with the diaphragm.
So the phrenic-spleenic ligament goes from the diaphragm to the spleen. Now the spleen is also indirectly supported by one more thing. So if you add the large intestine right here, there's a ligament attached to the left colic flexure that goes to the diaphragm.
And this one is called the phrenic-colic ligament, which the spleen rests on. So this ligament indirectly supports the spleen, by providing it with a nice bed for the spleen to rest on. So that was a video about the anatomy of the spleen, and I hope that was helpful.