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CRACK MRCS
  • 7/5/2025
Transcript
00:00Hello everyone, this is João from KenHub and welcome to another anatomy tutorial where this
00:05time I'm going to be talking about none other than the spleen and to do so I'm going to be
00:11essentially exploring these two images that you see here on the screen. So on the left side we're
00:18looking at the diaphragmatic surface of the spleen and here we see then on the right side
00:25the visceral surface of the spleen. The spleen happens to be a forgotten one of those forgotten
00:34organs that sometimes you ask what is what does it do and here right now we have the highlighted
00:40spleen from an interior view of the abdomen where you see a little bit of the liver here retracted
00:47and the pancreas a little bit of the colon and we just have a few cuts here because we just removed
00:53a few structures so we can then expose the spleen. So what is exactly the spleen and what does it do?
01:01It is the largest immunological organ of your body and measures about 12 centimeters in length
01:08and weighing approximately 150 grams. However this weight may vary from individual to individual.
01:16the spleen is a highly vascularized organ and is purple in color. It lies intraperitoneally in the
01:24left hypochondriac region between the 9th and 12th ribs just inferior to the diaphragm which we also see
01:33a little bit here on this image the diaphragm. This organ is surrounded by a layer of fibroelastic tissue
01:40and its main functions are associated to immune responses in our body, synthesis of antibodies,
01:51filtration of blood, lymphopoiesis, and phagocytosis. Now in order to help you remember the macroscopic
01:59anatomy of the spleen I have here a few helpful hints. The spleen has two borders a superior and an inferior
02:07one, two extremities, an anterior and a posterior extremity, and two surfaces that I showed you before
02:15and we have here the images a visceral one and a diaphragmatic surface. So let's begin by looking at
02:22the borders of the spleen starting with the superior border which you see here highlighted on both of
02:28these images. The superior border of this organ also known as the upper margin of the spleen
02:34forms the border between the gastric and diaphragmatic surfaces. There is also this margin here that
02:43you see now highlighted which is then the inferior margin of the spleen. It's also known as the lower
02:49margin. It is the border between the diaphragmatic and visceral surfaces. Now let's take a look at the
02:57two extremities of the spleen starting with this one that you now see highlighted. This is then the
03:02anterior extremity of the spleen. The anterior extremity of the spleen is basically the most
03:08anterior part of this organ seen here highlighted. The other extremity which is in this portion we see
03:15here highlighted is known as the posterior extremity of the spleen and it is the posterior most end of
03:24this organ which is of course known and we name it the posterior extremity. Let's take a look now at
03:32the surfaces of the spleen starting with the diaphragmatic surface. Now what we have here on
03:39this image is a cross section of the spleen done at the hilum of the spleen which is found right about
03:46here and you can see on both of these images highlighted in green the diaphragmatic surface of the
03:52spleen. Now as you can see it is a convex surface facing the diaphragm. Now this smooth surface is
04:00directed upwards and is in relation with the under surface of the diaphragm. The next part of the
04:08spleen that I'm going to be highlighting here is known as the gastric surface of the spleen which is
04:13then found on the visceral surface of the spleen and the visceral surface of the spleen it can be divided
04:21into three subsurfaces. One of them that we're looking right now is the gastric surface of the spleen.
04:28Now as the name indicates this is the portion of the spleen that is in direct contact with the posterior
04:36wall of the stomach. This is a broad concave surface which is directed upward lightly forward and towards
04:45the middle and it is then one of the three concave visceral surfaces of the spleen. The next visceral
04:52surface is the colic surface of the spleen seen here highlighted in green. Wow this even rhymes.
04:59Spleen and green I think this is going to happen throughout the tutorial. Now this surface is in
05:05contact with the colon. The spleen sits upon the left colic flexure or the splenic flexure which is
05:14the curvature between the transverse colon and the descending colon. The third visceral surface of
05:21the spleen we will look at is the renal surface of the spleen which is seen on both of these images
05:28highlighted in green. It is the lower surface of the spleen that is related to the upper part of the
05:34anterior surface of the left kidney. Now so far we have looked at the borders extremities and surfaces
05:41of the spleen. Now let's see how this organ is suspended in the retroperitoneal space. The spleen
05:48is surrounded by the peritoneum and the foldings of the peritoneum form two ligaments, two very important
05:56ligaments, one of these being the gastrosplenic ligament seen here highlighted in green. The gastrosplenic
06:03ligament stretches between the greater curvature of the stomach to the hilum of the spleen which is
06:11this area here where all these vessels are found. The other ligament formed by the folding of the
06:17peritoneum is the spleen or renal ligament. This ligament connects the left kidney with the spleen
06:24also at the hilum of the spleen. In addition to the peritoneum the spleen is also covered by
06:32a fibroelastic connective tissue known as the fibrosplenic capsule. So as I just said this is a
06:38fibroelastic connective tissue because the spleen is a very soft organ. This fibrous capsule helps the
06:47spleen maintain a relatively constant external shape. The next structure of the spleen we will look at
06:54here is known as the hilum or the splenic hilum as I mentioned before. It is the entry and exit site of
07:02the splenic vessels located between the gastric and renal surfaces of the spleen. Now as I mentioned
07:10earlier here we also find the gastroxplenic and splenorenal ligaments as you remember well when we
07:19looked at these structures. And please note that this part of the spleen is not covered by
07:25fibrosplenic capsule or the peritoneum. As we saw in the previous slide the blood vessels of the spleen
07:33just pass through the splenic hilum. One very important vessel that passes through the hilum and
07:38supplies oxygenated blood to the spleen is this one that we see here highlighted in green on both of these
07:45images. It is the splenic artery and as I said this supplies oxygenated blood to the spleen. This
07:53artery is the third branch of the celiac trunk as well as being the largest branch and it reaches
08:01the splenic hilum by passing through the splenorenal ligament. The splenic artery then divides into about
08:08six branches which enter the spleen at the hilum. The next structure we're going to be seeing here
08:14highlighted is then a vein. This is the splenic vein arising from the hilum and drains venous blood
08:21from the segmental splenic veins. It courses behind the pancreatic body joining the superior mesenteric
08:28vein towards the hepatic portal vein. The next structure we're going to be highlighting here is
08:33known as the splenic pulp. From a structural point of view the spleen is comprised of the splenic pulp
08:41and the trabeculae of the spleen. Now the splenic pulp is a mesh of fine reticular connective tissue
08:48that is found between the trabeculae of the spleen. There are two types of splenic pulp. The red pulp
08:57which gives the spleen its soft spongy consistency and it is comprised of splenic sinuses
09:05engorged with blood. There's also splenic cords and a marginal zone that borders the white pulp. The
09:14function of the red pulp is to act as a mechanical filtration of red blood cells clearing out defective
09:23as well as aging erythrocytes. The other type of splenic pulp is the white pulp. This one contains
09:31aggregations of lymphocytes varying in sites that are known as the splenic nodules or malpigian
09:38corpuscles or bodies. These malpigian corpuscles are composed of B lymphocyte rich lymphoid follicles
09:48and T lymphocyte rich peri-arteriolar lymphoid sheets also known as PALs. The function of the white pulp is to
09:59facilitate an active immune response through the humeral and cell mediated pathways. The next
10:06structure we're going to be highlighting here is known as the trabeculae of the spleen. These are
10:13connective tissue partitions that extend from the hilum and fibrous capsule penetrating into the spleen
10:20and dividing the splenic tissue into small chambers. Now these small chambers contain blood vessels which
10:28are the trabecular arteries and veins which happen to be the next topic that we're going to or the next
10:34structures we're going to be highlighting here in green. All these dots are showing then the trabecular
10:40arteries which are small branches of the splenic arteries and are transmitted through the splenic pulp.
10:47They are enchanted by the lymphatic aggregations of white pulp. Now these vessels are extremely ramified,
10:55so a lot of branches. The other structures that we see here in blue but now we're changing them or
11:02highlighting into green are the trabecular veins. So they're also seen here in the pulp of the spleen
11:09and receive deoxygenated blood from the pulp veins. They drain into the splenic vein which in turn drains
11:17into the hepatic portal vein. Before we conclude this tutorial I would like to add a few clinical notes.
11:24To be more specific I will add the two most common clinical points related to the spleen. These include
11:31then spleenomegaly which is the enlargement of the spleen due to hematological disease and also rupture
11:39of the spleen due to trauma. Well the spleen is not a vital organ which means that its functions are not
11:46useful for you to be alive. So the treatment for both of these conditions is then complete removal or a
11:53procedure which we call then splenectomy. Treated damage to the spleen can quickly lead to massive
11:59internal hemorrhage and eventual death. Now that you just completed this video tutorial,
12:06that is time for you to continue your learning experience by testing and also applying your
12:11knowledge. There are three ways you can do so here at KenHub. The first one is by clicking on our start
12:17training button. The second one is by browsing through our related articles library and the third one is
12:24by checking out our atlas. Now good luck everyone and I will see you next time.