hello everybody and welcome back to another Anatomy tutorial last week we looked at the peritoneal cavity and the organs that filled the peritoneal cavity as well as looking at how to divide the peritoneal cavity into various different spaces now this week we're going to look at the retroperitoneum I'm going to show you how to identify the organs that fill the retroperitoneum as well as showing you how to divide the retroperitoneum into three distinct spaces so let's start by having a look at the schematic and identifying the organs and then going across to a CT scan and looking at those organs there then we'll come back to the schematic and I'll show you how to divide the retroperitoneum so this is a picture from last week's talk and if you haven't looked at the peritoneal talk I'm going to link it above here we can see anteriorly everything shaded in green is our peritoneal cavity posterior to that retro to that is our retroperitoneum which is shaded in this light blue color we can see this green line is our parietal peritoneum which is the lining of that peritoneal cavity you can see our schematic shows a pancreas coming across here the ansonet head body and tail the kidneys the left and the right kidney as well as the adrenal glands that lies Superior to those kidneys and then we can see our aorta and our inferior vena cava these are all retroperitoneal structures if we were to head down in the abdomen a little bit further inferiorly we can still see our pancreas coming across the abdomen here our second part of the duodenum as it heads down inferiorly before crossing over we have our ascending colon on the patient's right and our descending colon on the patient's left we can still see our aorta and our inferior vena cava as well as our left and our right kidneys we've lost those adrenal glands because we're a bit lower down now posteriorly we've got muscles here we've got our psoas muscles that will head down towards the pelvis eventually join with the iliacus muscles as well as our quadratus lumborum muscles and they're aligned by a fascia which we're going to talk about later so let's have a look at a CT scan and find those organs on the scan so here we have an axial slice CT scan it's a normal scan of the abdomen and as always I'm going to start in the thorax when we're looking at this abdomen so let's scroll all the way up to the thorax and then head our way into the abdomen so as we scroll inferiorly we can see our liver coming into view on the patient's right hand side and we'll see our spleen coming into view on the patient's left hand side we can see the diaphragm here separating the thoracic cavity from the abdominal cavity now the first retroperitoneal organs that we'll see are our adrenal glands so I'm going to show you how to find those now they can sometimes be quite difficult to see they lie superior to the superior pole of the kidney we can see our left adrenal gland here it's got two limbs looks like an arrow pointing forward on the patient so you can see that adrenal gland is superior and slightly anterior to that Superior pole of the left kidney and the same on the right hand side we can see our right adrenal gland there now as we scroll down further we will see our kidneys come into view and you'll note that the kidneys are surrounded by this dark fat which will become important when we separate the retroperitoneum into its various different spaces so let's follow those kidneys all the way down and just see them down to the inferior Pole we can scroll back up to the high limb of the kidney where we should see our left renal vein coming across the aorta there as well as our right renal vein heading into the inferior vena cava here you can also see our renal arteries as well then this is where our collecting system becomes our proximal ureter that heads down towards the pelvis along that front edge of the psoas muscle now let's Identify some of the gastrointestinal structures that are in the retroperitoneum we'll start by looking at the duodenum so the stomach is an intraperitoneal structure and as it gives off the first part of the duodenum the Judaism heads backwards and becomes a retroperitoneal structure and that moment it becomes retroperitoneal it's the second part of the duodenum and that second part hits inferiorly crosses the midline heads superiorly up before becoming the jejunum and becoming an intraperitoneal structure again so let's start again at the stomach and we can find the duodenum from the stomach so here's our esophagus coming into the stomach the stomach heads around a j shape like that again and as we follow the stomach down we'll get down to the pylorus into the first part of the Jordanian that's not a retroperating your structure the second part D2 is a retroperitoneal structure we can follow D2 down before it crosses the midline which is our third part of the duodenum D3 and then we can scroll up superiorly as that fourth part of the duodenum comes and turns into the judging and the DJ Fletcher there then after D4 becomes an intra peritoneal structure so D2 3 and 4 are all retroperitoneal and here to that we should see our pancreas here let's find the pancreas a nice way to find the pancreas is to find your SMA your super Superior mesenteric artery and your pancreas wraps around that SMA so you can see the Antonette head body of our pancreas as we head out the tail of the pancreas should go towards the spleen now this bit of tail of pancreas that you see sticking out is actually an intra peritoneal structure so I'll answer it head and body are retroperitoneal they've only got one lining of parietal peritoneum on it but this pancreas actually has a bit of peritoneum wrapping all the way around so we consider the tail the distal portion of the pancreas and intraperitoneal structure we then have our ascending and descending colon so if we scroll down inferiority we should see our descending colon here on the patient's left hand side and our ascending colon on the right hand side so those are our retroperitoneal structures let's go and look at how we can divide the Retro peritoneum into three distinct spaces and I'm going to go back to our schematic to show you how we do that so as we can see in the schematic everything shaded in light blue is our retroperitoneum and we can see we can divide this retroperitoneum with these fascial planes that separate the peritoneum into different spaces we can see there's an anterior space here which is known as our anterior pararenal space p-a-r-a pararenal space our anterior pararenal space that has our pancreas our duodenum as well as our ascending and descending colons so you can see these are all gastrointestinal structures that fill this space so some people like to call it the gastrointestinal space this is our anterior paroreenal space the boundaries of that space well anteriorly we have our parietal peritoneum making up the anterior border here posteriorly this is what's known as our anterior renal fascia you can see this blue line coming across here is our anterior renal fascia which is also known as gerota's fascia you'll hear that commonly used gerota's fascia anterior renal fascia on the sides here you can see in Gray is our lateral conal fascia where our anteriorenal fascia and our posterior renal fascia combine to form this lateral conal fascia that makes up the lateral borders of our anterior pararenal space or our gastrointestinal space then posterior to that we have our kidneys filling a space that's known as the peri-renal space p-e-r-i peri-renal space this peri-renal space houses our kidneys and our adrenal glands as well as the proximal ureters and the vessels going into the hilum of the kidney we can see that the kidneys were surrounded by fat as we saw on that CT scan so this also has fat filling the space we know that this anterior border is gerota's fascia or our anterior renal fascia and then posteriorly we have a slightly thicker fascia here called Zucker candles fascia or our posterior renal fascia so duratus fascia anteriorly Zucker candles fascia posteriorly if you find it easier to remember anterior renal fasciae and posterior renal fascia you can see they head towards the mid lane now some people say that these fascists actually connect and there is a debate because sometimes when fluid falls in the space there is crossover between the two spaces and as you can see I've drawn a dotted line across here to to say that sometimes they join sometimes it doesn't sometimes these are distinct Spaces by themselves then we had an anterior pararenal space now we have a posterior para renal space the anterior border of which is our zuka candles fascia or our posterior renal fascia and then the posterior border here is represented by this purple line that's our transmissile is fascia that comes along the anterior border of our psoas and our quadratus lumborin muscle and as I'll show you in our next CT scan this is all just filled with fat so you can see dark fat on a CT scan filling this area and sometimes when we take an x-ray we see this stripe of fattier lining the abdomen which is our pre-peritoneal fat there coming from our retroperitoneum here heading all the way around so this is our posterior pararenal space we've made our three spaces now some people like to divide it slightly further and make a compartment here by itself which doesn't have defined fascial borders but we call it the compartment of the greater vessels so we can see our aorta and our inferior vena cava and that actually has communication with our posterior metastinum coming up forward so some people call this a distinct space the compartment of our greater vessels and some people call this vertebral body as well as our psoas and quadratus lump form call this our posterior space which is technically not a retroperitoneal space that's a retro retroperitoneum outside of the peritoneum there so we've seen where these planes intersect on an axial slice now it's sometimes important to know that this renal space is peri-renal space heads superiorly and on the right hand side there's a section of liver that doesn't actually have parietal peritoneum attaching it just goes liver straight to diaphragm there's a free bit of liver there and this peri-renal space superiorly communicates with that free edge of the liver on the patient's left hand side that that goes up to the left sub forenic or left diaphragm on the top heading down inferiorly that peri-renal space the anterior and posterior renal fascia or our gerotas and Zucker candles fascia fuse to form a combined interfacial plane which I can show you on a lateral section here so we get our bearings anterior here is our peritoneal cavity we can see our duodenum crossing the midline our descending or our ascending colon on this side filling our anterior pararenal space now the inferior borders of this space are less well defined and often when you get fluid collecting in here that can actually track into the pelvis we can see our peri-renal space here with our adrenal gland and our kidneys anteriorly is our gerotus fascia posteriorly is our Zucker candles fascia they fuse to form the combined interfacial plane and then we've got this fat fold space here our posterior pararenal space which is a posterior border of our transversalis fascia so I'm going to show you a CT scan that has some pathology and makes these fascial planes a lot easier to identify so let's have a look at that so we have an axial slice CT scan here and a patient that has a disease called retroperitoneal fibrosis and you can see this low attenuating soft tissue around the aorta which is calcified and has atherosclerosis and that pools all of the structures surrounding it towards the aorta there but you also get this fibrosis that makes Alto rotis fascia and our zocal candles fascia a bit thicker and a bit easier to see on the CT scan so if we orientate ourselves we can see our right kidney and our left kidney we can see that peri-renal space quite clearly here anterior renal fascia or arterotus fascia coming behind the descending colon we can see how Zucker candles fascia as well let's try and see it clearer here joining our anteriorenal fascia Orchard fascia forming our lateral conal fascia before it then goes and fuses with our parietal peritoneum so you can see that space really clearly here posterior to that so we've got our Zucker candles fascia our posterior renal fascia making the anterior border of our posterior pararenal space where we have the transversalis fascia making up that posterior border you can see the fat in there heading all the way around to the side of the abdomen there as we head inferiorly we'll see that our gerota's fashion our Circa candles fascia come together to fuse and that's our combined interfacial plane there we can head up superiorly and look at our gastrointestinal compartment where we have our pancreas coming across here there will be parietal peritoneum coming across that pancreas going to the anterior border of this descending colon we can also look for our duodename here there's some contrast in the stomach as you can see so we can follow this quite nicely we'll be able to see the duodenum hitting posteriorly down inferiorly before crossing the midline D3 hitting up superiorly D4 before going at our DJ Fletcher to our jejunum so all of that is retroperitoneal we can see that anterior to derotis fascia here will be our anterior para renal space that has our duodenum our descending and ascending colon as well as our pancreas coming forward as we head up superiorly we can see then our adrenal glands still within our peri-renal space and we can see our posterior pararenal space Also closing out here and this right hand peri-renal space will eventually come to this free border of the liver which doesn't have any parietal peritoneum it comes in direct contact with that right diaphragm on the left hand side that left peri-renal space opens up to that left diaphragm there so there we have it we can split the retroperating him into three different segments we can also look at an x-ray I thought I'd be interesting to show you as we see that posterior pararenal space coming round with a fat in that space we can see on an X-ray we can see that pre-peritoneal fat stripe coming along here we can often think that this is air within the abdomen but that's just that retroperitoneal fat coming around the sides of the abdomen there the posterior border of which is our transversalis fascia and the anterior border by the time it gets to here is actually our peritoneum so it's gone the outside of our peritoneal cavity so I hope that helps I hope you can look at the retroperitoneum and be able to split it into its three compartments the anterior pararenal space the peri-renal space and our posterior pararenal space and then identify the various things that fill those spaces and whenever we have pathology if we have a renal cyst that bursts we'll see it will only fill those particular spaces so when you know the spaces it becomes a bit easier to identify where the pathology is in itself so if you've liked the video I'd encourage you to please give it a like show me that you've liked it as well as leaving a comment below as to what other videos you'd like me to do and as always if you haven't subscribed to the channel I'd love if you would do that share it with someone that might find it helpful and until next time I'll see you all goodbye