Appendicitis pain anatomy

i want to talk about the anatomy of the appendix or more so i want to talk about pain from the appendix so appendicitis an inflamed appendix um gives a fairly classical description of pain starting para umbilical that is around the belly button that then moves towards the right why well the anatomy explains why and as we go we'll also pick out some other fun things that explain other things about appendicitis and stuff [Music] okay what's our toolkit what do we need to build well we need to look at the anatomy of the appendix we need to think about the innovation of the appendix if we're thinking about pain and we need to think about the peritoneum and then we can build up that stuff and you'll anyway right okay so how do we find the appendix well the appendix is in the lower right quadrant so let's dissect to find the appendix we need to find the cecum the cecum is the first part of the large intestine so it's the first part of the ascending large colon it's down here if i take off the small bowel we can see it a little better here it is so the cecum is like this blind ending pouch and it receives stuff from the small intestine so the ielium passes its content into the seachem oh look this one opens up so we've got the ileocecal valve here okay the appendix is round here somewhere where the appendix isn't out pouching from the cecum so if if the gastrointestinal tract is a tube the appendix is another little tube pouching from it so there'll be a hole here and i can see a hole there and where the appendix comes out of the cecum that's fairly reliable that's kind of the same in most people ah there it is so there's the appendix okay so we've we've found the appendix that feels like a good start the appendix's full name is the vermiform appendix vermiform vermi form worm shaped appendix means an appendage like an appendix in the back of a book it's like a you know it's a bit that's hanging on right so vermiform appendix and it's you know six to ten centimeters long if that's the cecum then we can see that it's kind of posterior and inferior in in origin and this one this one is actually retro sequel and it is it is a hollow tube it's like another blind ending tube as an out outpouching of the gastrointestinal tract it has all of the typical layers of the gastrointestinal tract but there's quite a lot of lymphoid tissue in the submucosa the appendix is not vital to life so it can be removed and it does seem to have at least one function one use um as well as being you know if it's got lymphoid tissue in there then there are going to be immune cells in there but also it seems to have a role in maybe storing the good bacteria of the gut when we have a gastrointestinal illness and our gi tract is tracked as flushed out by diarrhea and vomiting to clear all the bacteria out the bacteria can repopulate the gut more quickly from the stool that hangs around in the appendix that's the the current thinking anyway now although i say it comes reliably from the same spot on the cecum where it goes to is quite variable this is a retro sql version i think about 70 of people maybe have that maybe 75 of people so if the cecum lies like this the appendix is running kind of posteriorly behind it retro sequel and this one this one is running inferiorly from the sequin this would be subsequent which probably around 20 of people have that means about 95 of people have either a retro sql appendix or a subsequent appendix but it also can disappear often in other directions that well obviously if somebody has an inflamed appendix that will um you know give the surgeon a little bit of interest in finding it but also it can affect the symptoms of pain okay so what is um appendicitis then well itis refers to an inflammation of a tissue so we have inflammation of the appendix because we have this opening into the appendix from the cecum and we have this narrow tube running down the appendix that could become blocked it could become blocked by a fecalif that's like a hard stony fecal matter that could block that tube which is what tends to cause appendicitis in in adults um older people certainly you know older than 20 25 but in younger people the lymphoid tissue inside the appendix itself proliferates it expands it gets bigger it gets thicker so that lymphoid tissue can expand so much that it actually occludes the lumen of the appendix that that's more common in younger people that's a more common cause of appendicitis once the appendix becomes inflamed then the cells of the appendix can become necrotic so the cells die the appendix can then burst because if the cells die those walls those layers become weaker if the appendix burst then you have can have inflammation extending into the the peritoneal cavity into the abdominal cavity and that is a bad thing that's a much bigger space so this problem could get worse so the idea is that we recognize the signs and symptoms of appendicitis nice and early men tend to be very bad at this because we just oh it's fine go away you know it's nothing women tend to be much better i know i'm being a bit general here but this is from statistics this is this is based in evidence uh women are much better at looking after themselves than men so men will often put it off later but you must recognize the signs and symptoms of developing appendicitis so that you can fix the problem often surgically sometimes not and one of the major signs that i think is part of common knowledge suddenly it gets taught to medical students is that sense of pain starting kind of a bit more general around the umbilical region and then moving towards the lower right quadrant okay so why so the appendix is part of the mid-gut embryologically speaking which helps us remember the blood supply so the blood supply to the appendix is similar to other parts of the mid gut the blood supply to the appendix is from the superior mesenteric artery which is a branch of the aorta and the superior mesenteric artery is one of the three anterior branches of the aorta supplying blood to the gastrointestinal tract so the superior mesenteric artery sends various arteries off eventually gets to the appendix not too surprisingly as the appendicular artery now the nerves will follow the arteries so they'll they'll take the same sort of route um and what sort of innovation do you need to the appendix or to the gastrointestinal tract well you need autonomic innervation it's not somatic it's not of the body skeletal muscle skin that sort of thing it's it's autonomic it's like automatic stuff so there are sympathetic and parasympathetic motor fibers running to the appendix and what we find around the celiac trunk and the superior mesenteric artery we find plexuses so there's a superior mesenteric plexus it's like um it's like wiring there's a whole bunch of cables coming together here some of those parasympathetic nerves are coming from the vagus nerve and the sympathetic nerves are coming from thoracic levels of the vertebrae and they're meeting down here we've got a mixed plexus and those nerves run off a little find their way to the appendix and they can innervate the blood vessels supplying blood to the appendix and they can innervate the structures of the gastrointestinal tract in that region like they do elsewhere sensory nerves which is what we're really interested in because we're talking about pain visceral afferents as we might call them so sensory nerves from viscera from organs will run back along the same route because if you're wiring something up you would wouldn't you so visceral afferents from the appendix will run up to the superior mesenteric plexus and then they'll run back in following the sympathetic nerves into the spinal cord at the t10 level now remember sympathetic and parasympathetic are motor so they're going that way and the visceral afferents are sensory so they're going that way but essentially the nerve sensing stretch pain whatever from the appendix will enter the spinal cord at the thoracic 10 level so the appendix is inflamed visceral afferent fibers are carrying that sensory information back to the central nervous system and the brain so the brain knows what's going on those fibers enter the spinal cord at the t10 level up in the thoracic level and then they are conveyed up to the brain the brain gets this information and the brain isn't used to perceiving pain from organs at least hopefully it isn't so it is used to perceiving pain and sensory information coming in from the skin at various levels and the t10 level for skin is around the umbilical region so the belly button region so the skin here it's sensory fibers with somatic sensory fibers things that we're used to perceiving sensations from those fibers also run back into the spinal cord of the t10 level and up to the brain so the brain is aware that this pain information is coming in but it assumes it must be coming from the skin so the person feels kind of vague pain localized around the umbilicus this is what we call referred pain this is quite a good example of it so you've got your middle aged man who's got this pain developing he's probably a bit like me he just says it's fine it's bad so i'll walk it off and then over probably a period of days that pain starts to shift and move towards the right now why what's happening to the innovation to cause that let's talk about peritoneum all right peritoneum peritoneum is one of those bits of the body that once you when you don't know about it a lot of things don't make sense and when you do know about it you realize how important it is peritoneum is a thin serous membrane is that a feather a bit of paper um a thin serous membrane meaning it's largely connected tissue it's not very thick and it produces a little bit of fluid it has themselves in there making fluid and it lines the abdominal cavity and in fact it covers up the kidneys and all these blood vessels because it's lining the abdominal cavity the spleen is another matter we'll gloss over that and the peritoneum lines the inside of the anterior abdominal wall so it goes all the way around here it's like it's a completely enclosed bag and the peritoneum lining the abdominal walls it's also lining the inside of the muscles here is called parietal peritoneum and in the embryo we've got a bit of a bit of gut tube so the gi tract starts to form under here and pushes out and in doing so it also gets covered in peritoneum it's the same sheet it's one continuous sheet but this peritoneum covering the organ we call visceral peritoneum and in doing so we've made a a two-layered mesentery it's still peritoneum it's the same stuff but the mesentery allows bits of the gi tract to be mobile allows blood vessels and nerves to get to and from it so peritoneum now that visceral peritoneum covering the organ isn't really set up for high quality sensory detection right so it doesn't really it's not very good at detecting pain and pressure and things like that it might be able to detect stretch and irritation and so on um but it's it's not an accurate sensory apparatus whereas the parietal peritoneum has formed with the body wall which means it has somatic innervation somatic means of the body so it's receiving the same somatic innervation as the skin so the parietal peritoneum is actually quite good at detecting um pain pressure damage temperature all those somatic things a bit like the skin is right okay so how does that relate to our story it's got a hole in it well all right use your imagination here's our appendix is here right so our parietal peritoneum is running around here as the appendix gets worse and worse and its inflammation gets worse and worse its inflammation starts to spread it's going to eventually irritate the parietal peritoneum and when it does that because the parietal peritoneum is much more accurate at sensing stuff like this the pain becomes more localized to where the appendix really is so of course when you first feel pain in the center that's not where the appendix is this is referred pain caused by those mechanisms we talked about earlier but as the inflammation extends as the appendix gets worse as the inflammation gets worse and as it starts to irritate the parietal peritoneum then the parietal peritoneum that actually is where it is that actually is where the appendix is starts to send pain signals back to the brain and the brain is able to accurately say oh that's that's that's over there on the in the lower right quadrant and that's why the pain shifts from the umbilicus to the lower right quadrant as the appendicitis um develops one other bit of fun while i'm on my knees while we're down here okay see this muscle here this is uh source major it's a hip flexor meaning that it it flexes it flexes the hip right it's a big muscle a big hip flexor now look if i put the appendix so this is a retrosecal appendix right if i put this in it's right up against psoas major so psoas major if you flex the right hip can irritate an inflamed appendix if you've got an appendix that's inflamed and it's a bit sensitive flex in your right hip will move so as major so as major will get fatter thinner fatter thinner rub up against the appendix and and make it not very happy and cause more pain that could be useful if you're trying to work all this out so that quite complex anatomy describes the hopefully fairly well-known signs of pain shifting from the center to the right as appendicitis develops the other caveat i need to put in here is remember i said this is the classical presentation this is what we put in the textbooks but there's that five percent of the population where the appendix is is off somewhere else and if the appendix is pointing off somewhere else then those structures that we've talked about will be affected differently which means the pain will present differently so you still have to think hard and probably properly examine your patient to really work out what's going on i'm just an anatomist i got a phd in this stuff i'm just explaining the layout all right the medical stuff is for it's for medical people anyway but you got to admit that is some that is some cool anatomy and some cool working out by some very clever people right see you next week [Music] you

Channel: Sam Webster

Views: 70,572

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Id: IUEEq4tHpqY

Length: 17min 32sec (1052 seconds)

Published: Thu Nov 04 2021