[Music] this isn't your stomach your stomach is all the way up here instead this is your abdomen and in today's video with the help of the cadavers here in the lab we're going to discuss the anatomy of the abdominal region and help you understand exactly what you're feeling when your tummy hurts let's do this let's begin by discussing the musculoskeletal borders of the abdominal region now there's a couple different ways we can actually divide up the abdomen so that we have an understanding of exactly what we're looking at so in order to understand how we do that though there's a couple things we have to orient ourselves to so obviously you can see the rib cage here which is also going to include the sternum so the ribs that you're looking at primarily are going to be ribs one through ten and then the cartilages associated with them that are going to help attach it to the sternum but we also have ribs 11 and 12 which are going to be down here they just don't have those same cartilages the next thing we have to understand is going to be the clavicles and I know they're all the way up here and you're probably wondering why we're discussing the clavicles in relation to the abdomen but they will come in handy in just a moment we're also going to take note of the vertebral column specifically the lumbar region in the lumbar region is made up of five different lumbar vertebrae which we would say L1 L2 L3 L4 and L5 now we're also going to see it transitioning into the sacrum but the sacrum is more associated with the pelvic region which we're going to be discussing in a future video but then on either side of the sacrum we can see the oscoxy oscoxa just means hip bone but it's actually made up of three different bones that have fused together so this upper portion is going to be the one that's most relevant to us and this is going to be the ilium and we're really going to be looking at this Ridge line which is called the iliac crest that's going to be super useful in helping to determine the borders of that abdominal region so the first way we can kind of divide it up is the way that I learned and it's the more simple way to do it but we're going to see that it also comes with some issues and it's called the four quadrant scheme so to understand it there is a line that would be going down in the midline of the body so right through the sternum through the xiphoid process which is that pointy bit and then it's going to go down to the pubic symphysis which is what connects the two pubic bones of the oscoxy the next line is a transverse line the big would be going right about here it would be going right through the middle of the umbilicus or the belly button so what you end up with are four quadrants and that's what makes up the abdominal region so we would have a right and a left upper quadrant and then a right and left lower quadrant and for me when teaching basic anatomy I find that to be sufficient to help kind of describe my students the locations of the various structures inside of it but from a clinical perspective it's actually pretty insufficient and that's where we then move into the nine region scheme the nine region scheme is a little more complicated so what we're going to do this is where the clavicles come in handy we're going to go all the way up to the clavicles and find the exact middle of it and then we would draw an imaginary line going straight down and it would go through a piece of soft tissue that is obviously absent here on Jeffrey which is called the inguinal ligament so if we hit a line going from the middle of the clavicle down to the middle of the inguinal ligament that is called the midclavicular line and there would be a right and left midclavicular line the next line is actually called the intertubercular line and that is a line that goes from the tubercle of the iliac crest so now we're getting back to this Ridge line that I discussed earlier there's kind of a bump on the side here if we had a line that was going across and through the vertebral body the this I'm going to be the body the vertebral body here and going to the other tubercle that is that intertubercular line then this is where there's a little bit of variability and depending on who you ask the next line we could draw would be another horizontal line that would be going just below the tenth cartilage here and that is called the subcostal line but there's another line we could also draw that was just above it called the transpyloric line so what would be right here is the stomach and at the end of the stomach is something called the pylorus and if we had a line going straight through the pylorus that's that transpyloric line so either you could use either the subcostal or that transpyloric line some people will use both lines to just help further subdivide it but it really just kind of depends on who's teaching it but by having those lines so again we have the two midclavicular lines and then we have that intertubercular line then we have the subcostal line and that transpyloric line let's just say by doing that you then end up with nine regions in which we can divide the abdomen so if we start by just going right down the middle up here is what's known as the epigastric region then right below it would be that umbilical region this is again where you'd find the belly button and then below that that's where we'd find the hypogastric region if we come up here this is where we have the right and left hypochondriac regions then on either side of the umbilical region is where we'd have the right and left lateral or right and left lumbar regions which makes sense because they are associated with the lumbar vertebrae and then if we came down here we'd have the right and left inguinal regions now the reason why this nine scheme 9 region scheme is more useful from a clinical perspective is because it helps you dial in where someone might be feeling pain or referred pain pattern so if the clinician was palpating this area here and the patient was presenting with pain that is known as epigastric pain and that typically is going to you know align with a few different conditions and so that's very helpful from a diagnostic perspective and then one that a lot of people understand is if you have pain down here in the right inguinal region well that strongly correlates to appendicitis so further subdividing it is helpful from a clinical perspective but again going back if we're just teaching basic anatomy I personally find that four quadrant scheme to be adequate to help understand where the anatomy is but let's now go ahead and look inside the cadavers and see the anatomy of the abdominal cavity but real quick on I think the sponsor of today's video can Hub can is an online platform that brings together multiple effective learning tools to help you better understand and learn human anatomy anatomy is a truly wonderful science but it can be challenging to learn to say the least historically speaking students would have to rely on their textbooks and their note-taking skills to get them through the course kenhub however has found an immersive way to expand upon this you can navigate their platform like an anatomy Atlas clicking on specific regions to investigate they then have a combination of Articles and videos which act like a textbook as well as an instructor walking you through the lesson and if that wasn't enough they also have quizzes that are some of the most thorough I've ever seen utilizing images text and even sound as a narrator will say the anatomical terms out loud on top of that the quizzes come in multiple formats and are even customizable they can come with basic and advanced identification can be worded more like an exam or can be an intelligent mix where you can choose which one meets your needs the best the quizzes learn from your mistakes which can put an emphasis on previously wrongly answered questions in preparation for this video I referred to their abdominal Anatomy section it was awesome kenhub is so thorough and engaging it's a fantastic resource for those those going through school needing to study those who have already gone through school and just need a refresher and those super nerds out there who just want to know as much about their body as they possibly can if you're interested click the link in the description below and they'll give our audience a 10 discount on Ken Hub premium seriously if you're looking to actually learn your Anatomy kenhub is the place to go again that link is in the description below so before we discuss the internal anatomy of the abdomen let's first Orient ourselves to the muscular wall of the abdomen now first and foremost what you're looking at here is going to be the umbilicus or the belly button now the reason why we left it here is to give you just an idea of the depth between the skin and the muscles now if you remember what we were talking about with the quadrant Anatomy we had that line going down the midline which would go through the umbilicus and go down towards the pubis and then we had another line that would be going transversely through the umbilicus and so that would create those four quadrants so this also is just helping to orient us to what we are looking at here but the muscle I want to or the first muscle I want to discuss is going to be the rectus abdominis and we can see part of it here the rest of it is going to be enveloped in soft tissue which is known as the rectus sheath but the rectus abdominis is a paired strap muscle so there's going to be different components to it different segments to it on either side of the umbilicus and these are strap muscles and what they do is they Flex the lumbar vertebral column so you can think of it like doing a crunch this is going to form the anterior wall of the abdomen and running down the center of it is what's known as the Linea Alba just means white line now there is another muscle that is absent on this particular donor that would be in this region here called the pyramidalis now pyramidalis is actually going to put tension on the Linea Alba but it's missing in around 20 percent of the population and that means that this particular donor is part of that 20 percent but it's a very small muscle that is Pyramid shaped that puts pressure on that Linea Alba so that will also help form the anterior wall now to form the lateral wall what we're going to do is I'm going to move this a bit so we can see these muscles here so this is a small portion of what's known as the external oblique and it's a pretty massive muscle that will wrap around all the way up onto the thoracic cavity and we can see part of it right here but you'll notice that its fibers are going towards the midline this when it contracts unilaterally is going to help twist the body but if it contracts bilaterally it will work with rectus abdominis to help Flex that lumbar vertebral column what's cool is it's a layered or it's part of a layered system and I can flip this over and what you'll notice so if you look very closely you can see fibers again going towards the midline now they're going away from the midline and this is going to be the internal oblique its fibers are perpendicular to the external oblique but what's interesting is both of them including the one that's going to be underneath that we'll discuss a moment called transversus abdominis will turn into a tendon and that tendon is the sheet it forms what's called an aponeurosis that will then envelop the rectus abdominis creating that rectus sheath so all this white tissue here is actually tendon from the lateral abdominal body wall that is just enveloping that rectus abdominis but to go back to that transversus abdominis so this one there's only a small bit that we can see here on this particular dissection but the fibers are going in the transverse plane so when transversus abdominis contracts bilaterally so both sides at the same time it compresses the abdomen which is essential for just overall integrity and just uh you know stability of this region but if it contracts unilaterally it can help twist the body but on the same plane as transverse is subdominis but if we wrapped all the way around to the back which unfortunately we cannot see in this particular dissection is called the quadratus lumborum and the quadratus lumborum is the true back wall of the abdomen and I say true back because there are going to be two other muscles we'll discuss shortly that are more internal that some may consider to be part of that wall but I don't personally do that but quadratus lumborum is going to help just again you know keep with stability it's going to help do some lateral flexion but it is going to be that back wall so let's now go ahead and remove what we call the chest plate but also includes the anterior wall of the abdomen and as I do that and slide this out of frame of the camera we can now see many of the different organs and structures of the abdominal cavity now what separates the abdominal cavity from the thoracic cavity is going to be this skeletal muscle here called the diaphragm and diaphragm actually translates to fence or partition and it rests on top of this massive organ here called the liver but this is just a literal divider between the abdominal cavity and the thoracic cavity but it's obviously going to be essential for breathing but that is part of the respiratory system but this forms the upper border of that abdominal cavity what we also need to understand is there is tissue that lines both the organs and the internal wall of the abdominal cavity so if I bring back this chest plate what I'm going to do is I'm actually going to reflect it over so we can see the inside of it now this is rectus abdominis and rectus abdominis is encompassed again in that rectus sheath but it's also going to be coated on the internal surface with what's known as the parietal peritoneum the peritoneum is going to be a serous tissue that is a lubricating tissue so it secretes a fluid that is highly lubricating that is going to be very essential for all of the digestive processes but the parietal peritoneum is going to line the entire well not the entire but the vast majority of that abdominal cavity so if I pull this again out of frame that allows us to see in here and then we have to discuss what's called the visceral peritoneum so this is the small intestine encoding the small intestine is going to be peritoneum that'll fully Encompass it so visceral is just in reference to the guts so you're going to have visceral peritoneum that covers all of these intestines as well as the liver and many of the different structures inside of here now there's also what are called reflections of peritoneum and this is one example of that this is called the greater omentum now the greater omentum is basically just peritoneum that is folded on top of itself right so it'd be folded on top of the peritoneum that would be coding the small intestine now if I pull or reflect this liver back you can see the stomach and the greater momentum is would normally be connected to the greater curvature of the stomach we just dissected that away which allows us to see some of the other structures but this is an example of a peritoneal reflection there's also a less romantum and a couple of other structures that we can't really see here another thing we have to understand if I go ahead and reflect this greater momentum back and then we can see the small intestine so I'm going to move those out of the way we can see more of the peritoneum here there's also what are known as intraperitoneal and retroperitoneal structures so the small intestine are example of intraperitoneal structures that means they're just fully encompassed in peritoneum but there are other structures such as the kidneys which I'm actually touching a kidney right now you just can't see it because the anterior aspect of the kidney is covered in peritoneum this is an example of a retroperitoneal structure only the anterior aspect of it is touching the peritoneum that also includes say the super renal or adrenal glands I can pull this back and if I move the greater momentum back and this is the reason why we cut this away it allowed us to then see the pancreas the pancreas is another example of a retroperitoneal structure normally this would be completely covered by well not completely but mostly covered by peritoneum but also the duodenum is going to be retroperitone meal or again the vast majority of it so there are certain structures that are just completely behind this peritoneum and you may be wondering what does the peritoneum do the peritoneum and you can see this really well in this greater momentum is a great Avenue for blood vessels lymphatic vessels as well as nerves in some cases so it's basically just a really good way to get you know blood supply and innervation to structures throughout the abdominal cavity and that's what that peritoneum is going to be for so let's now go ahead and discuss the various structures and organs within the abdominal cavity as they relate to that four quadrant and nine region scheme and you're going to see just how useful laying out the abdomen like that is going to be so first if we just look at it from that four quadrant scheme which again for me for teaching basic anatomy I do find that to be sufficient if we do it like that you can see that the liver or at least most of the liver is going to be in that right upper quadrant now this particular liver I'm going to reflect the diaphragm back is actually a little bit deformed this particular donor we can see some cancer that metastasized from the colon and in fact this is partially part of their cause of death was going to be colon cancer that metastasized to the liver so that does deform the liver and increase its size a bit which means that the liver is now projecting into that left upper quadrant but primarily we would say that it is going to be in the right upper quadrant as would be the gallbladder now I can't show you the gallbladder because this donor had their gallbladder removed at some part and their some portion of their life but the gallbladder is also going to be in that right upper quadrant then behind we would then have the right kidney as well as the right adrenal gland are also going to be part of that right upper quadrant we can also see that the duodenum is going to be partially in that right upper quadrant as it's crossing over again this is where you're like some of these are not always going to line up perfectly because you have this midline going and the body didn't Orient itself based on these schema these schemes that we humans have developed so the duodenum can also start to project more towards that left upper quadrant but it's going to be mostly in that right upper quadrant but it's also going to start extending into lowers but again just kind of depends but that is going to be that right upper quadrant the left upper quadrant as I reflect the liver back again partially contains the liver but also will contain the stomach and then I can move it back and we can see the pancreas that's this yellow tissue here so the yellow so the pancreas is interesting it's both a digestive and an endocrine organ in the sense that it contributes pancreatic secretions to the digestive system but also produces hormones such as insulin and glucagon then we have the spleen the spleen is a really cool interesting organ it's partially lymphatic in nature but it also is where red blood cells will keep will end their life at where it'll rip apart the red blood cells but this is going to be in that left upper quadrant as would be the left kidney and that left adrenal gland now the greater momentum is going to be in those lower quadrants but if we reflect that back you can then see that the intestines are also going to be encompassing both that right and left lower quadrants then if we look at the large intestine now the large intestine is going to begin here at the cecum and the ascending colon are going to be in that right lower quadrant but then as it goes into the transverse colon which is coming up through here that is where you're starting to get and again if we put this back normally this is where you're like in the you know you're kind of like at that border but transverse colon can start getting in towards that those upper quadrants but it's also still kind of in the lower quadrant so it really kind of just depends on that individual's Anatomy but that transverse colon is going to come around and then we're going to start making our ways I move the small intestine into the descending colon which is again going to be in that left lower quadrant and then we start to go into the sigmoid from there it's actually going to start dipping down into the pelvic cavity and again we're going to discuss pelvic cavity in a future video the pelvic cavity is going to include you know the bladder reproductive tissues the rectum those types of things but that's where again we're it's just we'll leave that for a separate day but I also want to discuss muscles that I mentioned earlier so if we look back here you can see behind the peritoneum we have the psoas major and this white line the psoas minor these are hip flexor muscles that I mentioned some consider to be part of the back wall or that posterior wall of the abdomen or the abdominal cavity now personally I don't really see it that way I just see them belonging inside of the cavity itself instead of quadratus lomborm being that posterior wall but still you can see those right there now there and then plus there are plenty of other structures too that we can't see that are retro peritoneal such as the aorta that descending aorta that's going to go down the inferior vena cava so the aorta which would be about right here running along that left side of the vertebral column is going to deliver oxygenated blood to the lower body while the inferior vena cava which is on the right side heading towards the liver as I bring this back is going to be taking deoxygenated blood back towards the heart from that lower body but then there's accessory blood vessels like the renal artery renal vein there's a lot of things that we necessarily just can't see due to the nature of this dissection but that's you can see like how the four quadrant Anatomy will help but now if we just briefly discuss then that nine region scheme you can start to see how clinically that's going to make more sense so again like this region right here is the epigastric region and if I reflect the liver back you can see the stomach so if someone is experiencing some stomach issues say like gastritis it makes sense that they would have epigastric pain again if we come down here as I mentioned earlier this is the cecum and then we also have hanging off of it the appendix so the appendix if you have appendicitis it would make sense that that is also going to possibly present with pain in this inguinal region now to really quickly just touch on referred pain it's also important to understand that these structures don't have you know great innervation in terms of sending or your body processing brain process processing nociception pain meaning that sometimes the pain can start to like present in different areas as of when compared to their exact locations and that's why it's called referred pain again that's a whole that's a whole other can of worms just understand that when we start breaking down the abdominal cavity into you know those nine different regions it gets a little bit easier diagnostically to start figuring out or at least start trying to figure out where the pain or the issue might be but like real briefly if we're to say like in those hypochondriac regions that's going to be on these these right up right and left upper sides that's where you're getting the spleen that's where you're getting part of the liver that's where you're getting part of the stomach uh in that epigastric that's where you're getting part of the duodenum part of the pylorus part of the stomach in the umbilical region this is where you're getting a lot of the greater momentum but you're also getting transverse colon you're going to be getting part of the small intestines you're going to be getting a lot of the mesenteric vessels by the way the mesentery is part of the peritoneum as well this is what anchors the small intestine to the you know just to the various blood vessels into the body itself so your small intestine isn't just hanging around but inside of here you're going to find a lot of blood vessels and nerves lymphatic tissue that is all going there's going to be a giant network of that behind here in that umbilical region on the lateral regions this is or those lumbar regions this is where you're finding this is where you're finding like ascending colon as it's turning into the transverse colon as well as I move this up to the side descending colon as it's turning in into the sigmoid colon and then when we're getting into that hypogastric region this is where again you're still having more small intestine but then the upper portion of the bladder would kind of be pushing into this area this is Again part of the pelvic cavity but still you're also going to have the rectum kind of coming around in that area and then in that right and left inguinal areas is where you're also getting the sigmoid as well as you're getting the cecum and the appendix so again from a diagnostic standpoint it makes a lot of sense to really think about it in that nine region scheme but for me personally I find that four quadrant to be adequate when teaching basic anatomy but now this is just a small uh you know aspect of all the different anatomy and structures inside of here if we really started pulling these out and teasing it out you'd find many different structures in here but hopefully this gives you a pretty good understanding of how much is located inside of your abdomen so again just to really drill this home this is not your stomach this is your stomach so when your tummy is hurting when your stomach is hurting it's really your intestines but if we're to really figure out what exactly is hurting that's when we'd have to go okay is it hypogastric pain is it inguinal pain is it umbilical pain so on and so forth thanks for watching Everybody if you enjoyed today's video please consider giving it a like it's a super easy way to help support our Channel considering it tells YouTube this video is worthwhile and they're more likely to recommend it to other viewers be sure to click the link in the description below and get 10 off your kenhub premium subscription today again thanks for watching and I'll see you in the next video [Music] thank you