DIP Episode 345 - Some HY Cardiovascular Anatomy Scenarios

Okay, welcome. My name is Divine. This is episode 345 of the Divine Intervention Podcast. And in this podcast, I'm going to be going over some anatomy that's relevant to the USMD step one exam. I'll be going over a few like pieces, large veneers, just to illustrate certain key points. And I'll be focusing almost exclusively to the own cardiovascular anatomy. So, let's assume, for example, you're trying to perform an intercostal nerve block. And they tell you that, oh, how should an estetizing needle be introduced into the present thoracic cavity? Well, if you see a question like that, then I would want you to hopefully remember, is they want to go along the inferior edge of the rib. Right? Because again, the MDM is love to do this play on words when they know that, oh, people will see that something is happening. And when they see something is happening, or they've learned something in a certain way, if it's put in a different format, that is, you know, kind of similar, but just a little bit different. They don't take those as necessary precautions. So, essentially, the thing that's happening here is you're doing a nerve block. So, if you're doing a nerve block, you're trying to catch the artery. You're trying to hit the artery, right? So, you're going to go along the inferior edge of the rib in those circumstances. You're going to go along the inferior edge of the rib.

So, remember that along the inferior edge of the rib, that's where you have your intercostal bondolo vessels. Right? Intercostal bondolo vessels, you have the intercostal vein, it comes first. And then after that, you have the intercostal artery, it comes just below the intercostal vein. And then after that, you have the intercostal nerve. Right? So, you're going to get to the nerve third, if you're going with a needle in the inferior edge of the rib. Remember, you go to the superior edge of the rib. If you're trying to withdraw fluid from around the, from the, from around the lungs or whatever, if you're trying to do like a thaurus and teases, because you go above the superior edge of the rib, then you're essentially avoiding that intercostal bond, so that you don't injure them. Right? But if you're doing a nerve block, you're trying to hit that bond. Now, what if they give you a question about a patient and they tell you that, oh, you know, they give you like a chest texture and they tell you that, oh, this is a chest x-ray that was taking inspiration. And you notice that the person's diaphragm, on, you notice like some asymmetry, let me put it that way. Notice some asymmetry on the chest x-ray. You notice that while the right diaphragm is very high compared to the left diaphragm. Right? So, what would the cause be in those circumstances? Well, the thing is that diaphragm is asymmetry where you see like one diaphragm much higher than the other.

The thing should be thinking about on you, in the exams is if the, is the person having some kind of a diaphragmatic paralysis. Right? So, remember, the diaphragm is interviewed by the frenic nerve, right? C3, 4 and 5. Remember that mnemonic? The C3, 4, 5 keeps the diaphragm alive. Right? So, the venture remite, remember, the dossal remite is venture remite, right? So, the venture remite of the C3, C4 and C5 nerve roots, supply the, the frenic nerve, right? So, if the frenic nerve has been paralyzed, then the person is going to have diaphragmatic paralysis, right? diaphragmatic paralysis. So, again, whenever you see, again, these are all just classic things you love to test on the USML Is. If you see an image, right? And you notice that while one diaphragm is much higher than the other, then you want to think about diaphragm paralysis, you want to think about frenic nerve damage, you want to think about damage to C3, 4 and 5. And I just want to the quick tip bit I want to mention with regard to the frenic nerve that, you know, is exam worthy to know for sure, is that the frenic nerve remembers it runs anterior to the root of the lung, right? The root of the lung, you know, when it arises from the medius nerve, the frenic nerve runs anterior to the root of the lung. But the vigorous nerve, which is cranial nerve 10, actually runs posterior to the root of the lung, right? Runs posterior to the root of the lung.

Now, when did you give you a question about like a 25-year-old male, you know, the tell you that he's coming to the emergency room, his blood pressure is like 60 over 40, so it's very low, obviously, right? And the tell you that, you know, he just got stabbed in the chest on his way home from work, right? And the tell you that you can barely perceive any kinds of heart sounds, right? And then they say, oh, this person's symptoms are most likely due to the nerve to the knife traverse in what, right? And then one classic thing they can do is they can give you many different, uh, uh, liars of the heart, or so they can say, oh, uh, they're having these symptoms because the knife traverse the visceral layer of the pyro cavity, or let's say they say, oh, traverse the priodole of the fibrospericardium, or traverse the visceral layer of the serospiricardium, they just give you all this pill in words, right? Obviously, this person has cardiac tamponato. Remember, in cardiac tamponato, the person essentially has stuff, you know, like blood, for example, in the pyrocardial space, and because of that, the heart cannot fill with blood, right? Because that fluid is causing an external compression of the heart. If you get that external compression of the heart, that's going to be problematic, right? Because the heart cannot expand to fill with blood, right? So what layer, because the thing is if you get stabbed in the chest, it doesn't necessarily mean you have tamponato, right?

Because if you don't get to the heart perinkum itself, then you won't necessarily have any problems, right? But the thing is, this person having cardiac tamponato from like a stab, or remember, cardiac tamponato has a triad, right? Um, hypertension, GVD, and morphed heart cells, right? Again, GVD because your jubbal veins cannot drain into the heart, because the heart has the astolic dysfunction from being cramped around by fluid, right? So essentially, the thing that has happened here is that the knife has traversed the visceral layer of the serospheric heartium, right? The visceral layer of the serospheric heartium. Because the thing is, remember, the heart has two pericardial liars around it, right? It has the serospheric heartium, and then it has the fibrospericardium. The serospheric heartium is the part that is juxtaposed to the heart itself. The fibrospericardium is the part that is on the outside of the heart, right? Is more outward compared to the serospheric heartium. But don't forget, the serospheric heartium has two liars. It has the visceral layer, and it has the parietal layer, right? So if you're essentially going from the heart to the outside world, we have the heart, it's encased in the visceral serospheric heartium. And then that is for the encased in the parietal serospheric heartium. And then that is encased in the fibrospericardium, right?

So if, for example, you're going to damage your person's heart from a stub, don't do this obviously, but if a person's heart is damaged from a stub wound, right? You must have traversed the visceral serospheric heartium for the person to have those kinds of symptoms, right? And then what if they give you a question about like a newborn, they tell you that you know, he presents with cyanosis and you know, he's diagnosed with like tetralogy of the low. And then they tell you, what's the most likely cause of his cyanosis, right? And then let's say they give you a few options, right? So let me run through a few options with you here. So let's say one option is they tell you, oh, the reason this newborn is not a case because of blood flow, right? So let me give you the options blood flow from the left to the right side of the heart secondary to increase pulmonary venous pressures. Or I give you another option, I say, oh blood flow from the right to the left side of the heart secondary to increase eotic pressures. And then I give you another option that says blood flow from the left to the right side of the heart secondary to increase pressure in the doctor's arteriosus. And then I give you another option that says blood flow from the right to the left side of the heart secondary to increase pressures in the pulmonary arterial system. But if you think about it, if you think about it, what kind of answer do you want to go with?

Well, I'll really hope you're saying, okay, let me go with the fourth option that divine give, right? Remember, people that have tetralogy of low, right? There's classically four findings. Again, those four findings, they sound like a disparate series of findings, but they are not that disparate. They actually pretty consistent if you know what you're doing, right? Again, remember, embryologically, the thing that happens, and I'll answer this question in a bit, but let me give some pathways here to give some understanding. But embryologically, the thing that happens is that, you know, think of the heart as a box, right? And let's say, you know, you have the right ventricular one side, the left ventricular on the other side. Whenever you want to divide the ventricles, the thing that happens is you start off first by the muscular interventricular grain from the bottom, right? And then your eodico-pominary septum, right? So look at the name, eodico-pominary septum. It's a septum that devised the order from the pulmonary arteries, right? It's supposed to calm down and part of it, you know, is supposed to sort of kind of form some part of your membrane-inventricular septum, and that's supposed to divide the heart into two parts, right?

Like the membrane-inventricular septum is supposed to exactly because it's almost like something is growing from the top and there's something's growing from the bottom and you need to meet in the middle so you can perfectly divide the ventricles, right? So the thing that's going from the bottom is the muscular interventricular septum. The thing that's going from the top is the membrane-inventricular septum. The middle, right? And then divide the heart. So if for some bizarre reason, ready for some bizarre reason, the muscle interventricular septum is growing upwards, but your membrane-inventricular septum, you know, through the eodico-pominary septum, calms down to the right of center. If it doesn't meet the muscular interventricular septum in the middle, it just means it's to the right of center. And you can already begin to see some problems arising, right? First things first, you'll see that since they don't meet in the middle, right? There's going to be an obvious communication between the right and left ventricle. That's going to be a VSD, right? That's one of the findings in tetralogy of the law. And then another classic finding, right, is if you notice, since this eodico-pominary septum, right, grows to the right of center, the thing that's essentially happening in those circumstances, right? It's growing to the right of center.

The thing that's essentially happening in those circumstances is that your, the right side of your, like, because look at it, eodico-pominary septum, septum that divides the eodir from the pulmonary artery, right? If it's growing to the right of center, that means it's more right shifted. So that means it's going to be taken up some of the space that's taken by the, uh, normal pulmonary artery. So let's say the normal pulmonary artery with, is supposed to be like two centimeters. I'm just making up numbers here. But because this member, not sinterventricular septum, which again is almost like derived from the eodico-pominary septum, because it goes off to the right of center, right? The thing that happens is the diameter of the width, maybe like, oh, one centimeter, right? Obviously, that's not a no space for the pulmonary artery, right? So the person is going to have pulmonary stenosis. That's one of the findings, right? So if you notice that the person has pulmonary stenosis, well, obviously the right ventricle is going to have to work harder to pump blood out of the heart. So they're going to have right ventricle hypertrophy. And then, since they have right ventricle hypertrophy, right, again, that's going to cause like, you know, pulmonary hypertension, right side of the heart failure, right? But we see that, that septum, since it's growing to the right of center, the pulmonary artery is getting little space. So that means someone else is going to get that extra space.

That's going to be the eodir. That's the overriding eodir, right? So those are the four findings in the trilogy of phallop, right? Overriding the eodir, pulmonic stenosis, right ventricle hypertrophy, and a VSD, right? So because the right side of the heart has much higher pressures than the left side of the heart, blood is going to flow from the right ventricle to the left ventricle. When it flows in that direction, right? You're obviously sending the oxy-anithet blood to the rest of the body. So it's going to be some kind of sionotic shot. It's going to be a right to left sure. It's going to be sionotic, right? So the answer is going to be the fourth option, right? The reason this child is sionotic, right? It's because they have blood flow from the right to the left side of the heart, because of increased pressures in the pulmonary arterial system, right? Because again, they have pulmonary pulmonic stenosis, right? Pulmonic stenosis. Now, what if they give you a question about a 72-year-old male, and they tell you that it comes to the emergency room, you know, it has like CV abdominal pain, and they tell you that, oh, you know, they think that he's symptoms are because he has like a small bowel obstruction from an indirect inguinal hernia, right? And then they say, oh, what is the most likely finding of physical exam, right? So let me give you a few options, right? So let's assume what option is.

Oh, he symptoms are rising because of a bulge that is medial to the femoral artery pulse with a valve-solve of an uva. And then you see another answer that says, oh, a bulge medial to the inferior epigastric pulse with a valve-solve of an uva. Or you see another one that says arterial pulsations of the inferior epigastric vessels medial to a bulge elicited with a valve-solve of an uva. Or you see another option that says arterial pulsations of the inferior epigastric vessels lateral to a bulge elicited with the valve-solve of an uva. And then you see another answer that says a bulge lateral to the superior epigastric pulse elicited with a valve-solve of an uva. All right? And what are these options again? So you can kind of think about it, right? So the first one is a bulge. So this person we think they have an indirect inward or hernia, right? So we see the answers. A bulge medial to the femoral artery pulse with a valve-solve of an uva. And another one says a bulge medial to the inferior epigastric pulse with a valve-solve of an uva. And although one says arterial pulsations of the inferior epigastric vessels medial to a bulge elicited with the valve-solve of an uva. And another option says option D, right? Atherial pulsations of the inferior epigastric vessels lateral to a bulge elicited with a valve-solve of an uva. And then the fifth option says a bulge lateral to the superior epigastric pulse elicited with a valve-solve of an uva. Right? You see all these words again.

When you see all these words on an in-beaming example, you just freak out, right? So it's like how do you approach this again? Many of these questions that have these very confusing answers. It ended up being the easiest ones, right? The first thing you should always do when you're confronted with questions that this is ask yourself, what is the right answer supposed to be? Comment with the answer in your mind first. Before you start looking at the answer choices that I give it, right? So really the third option I gave is the best, right? It's the best. So if a person has an indirect and without her name, well think about it, right? I know this is not exactly, you know, cardio, but this is like vascular anatomy of some sort. So I want to emphasize this here because it's something that people tend to mess up a lot on an example, right? So this person has, can we say, 12 like an indirect and without her name? Well remember, these indirect and without her name is right? They arise lateral to the inferior epigastric vessels, right? They arise lateral to the inferior epigastric vessels, right? So the thing is, you can elicit these hernias by either like popping a bulge, right? Lateral to the inferior epigastric vessels, right? Or you can pop it up pulse medial to the bulge, right? From the hernia, right? It's just basically the same, just different ways of stating the same thing, right?

We know that these indirect and one of hernias, they are lateral to the inferior epigastric vessels. So if they are lateral to the inferior epigastric vessels, right? You will pop it the bulge of the hernia lateral to these vessels. But if you're looking at it from the perspective of the bulge of the hernia, you will pop it the inferior epigastric vessel pulse medial to the bulge, right? Again, it's just the exact same thing, right? It's just the exact same thing, it's just the exact same thing in these circumstances, right? So again, the third option I gave, right? Oh, arterial pulsations of the inferior epigastric vessels medial to a bulge elicited with the valve sovereign and over, that'll be the smart thing to pick in these circumstances, right? Now, what did they tell you that because again, every now and then the Mbimis love to give questions where a person is stabbed in a particular part of the thoracic cavity and they will ask you, oh, what is the structure that is most likely injured, right? So let's say for example, a person sustains a stab wound to the left intercostal space, right? Lateral to the body of the sternum. Remember, your sternum has multiple parts, right? It has like the manubrium and then he has the body, the body is like the larger part of the sternum, right? So the thing is if you, if you sustain a stab wound to the left intercostal space, lateral to the body of the sternum, what chamber of the heart would you most likely hit?

Well, the chamber of the heart you most likely hit, right? It's the right ventricle, right? But you notice the way I kind of did this plan where it's oh, you know, the left intercostal space lateral to the sternum body, the Mbimis knows that people's minds will kind of be all messed up and they'll say like, maybe it's some left part of the heart that is stabbed, no, right? Remember, the right ventricle constitutes the entire part of the heart. So because the right ventricle constitutes the the anterior part of the heart, if you stab even the left side of the sternum body, you're going to land on the right ventricle, right? So the answer to this is going to be, it's going to be a right ventricle, right? It's going to be, it's going to be a right ventricle, right? So now, what do they give you a question about a, you know, like a medical student or a physician, you know, trying to perform a thoracinthesis, right? They're trying to perform a thoracinthesis because you're trying to, you know, draw fluid from a person's puerocavity, right? And then they see, oh, before you encounter the internally in your costo muscles, right? The internal intercostal muscles, what, what structure, right? What structure of the person most likely traverse, right? And then let's say you get a bunch of options, right? So let's say you get an option that says, oh, before you hit the internal intercostal muscles, you're going to hit up the parietal purer.

And then let's say another option says, oh, you're going to traverse the external intercostal muscles first. And then let's say another option says, you're going to traverse the inner most intercostal muscles. And then let's say another option says, you're going to traverse the long parankhama. Well, what's going to be the right answer here? Well, I already hope you're saying, oh, divine, it's going to be the external intercostal muscles, right? Again, the layers of skin that you need to traverse to get to certain key structures in the body are generally pretty high yield for, for the USML Step 1 exam, right? So the thing is, let me let's think about it. So if you're introducing a thorac and t-seist needle into a person, right? To draw fluid, the first thing you're going to encounter is you're going to traverse the skin. We know that. That's pretty obvious. Now, after you traverse the skin, you're going to traverse the superficial fascia. After you traverse the superficial fascia, the next thing you're going to traverse at the external intercostal muscles, after you traverse the external intercostal muscles, you're going to traverse the internal intercostal muscles. After you traverse the internal intercostals, you're going to traverse the innermost intercostal muscles, right? And then after you traverse the innermost intercostal muscles, you're going to traverse the endothoracic fascia, right? You're going to traverse the endothoracic fascia.

And then after that, you're going to traverse the parietal plura, right? And then after they're going to get into the plural cavity, after you're getting to the plural cavity, you're obviously going to traverse the visceral plura. Then after you traverse the visceral plura, you're going to get to the long piring command itself, right? So I'm just going to read it off again. Again, you're going to go through skin, then superficial fascia, then external intercostals, then internal intercostals, then innermost intercostals, then the endothoracic fascia, then the parietal plura, you get to the plural cavity, and then after that, the visceral plura, and then the long piring command itself, right? So before you encounter the internal intercostal muscles, you're most likely going to traverse the external intercostal muscles, right? Now, um, because I want to try to keep this podcast short. So I think maybe, let me go ahead and, uh, let me, let me, let me, let me maybe go ahead and, and stop here. Again, I'll make more anatomy podcasts in the, in the future. So as I do at the end of every podcast, I go for one or one tutorial for many exams, right? Step one, step just again, step three, pre-clinical med school exams, third year shelf exams, and I also have a step two ck step three, you know, complex level two and three course coming up in November. On November 1st, we're going to work on test again processes.

We'll talk about test again strategies is the MBME test again strategy course is from two to four 30 p.m. Pacific standard time on, um, on on November 1st. And then from November 2nd to the 5th, we have a review course. It's going to spun over 24 hours and we cover about 2000 or more scenarios that quite across the different subjects, pedes, surgery, OB-guine, internal medicine, psych, neuro, multi-system processes and disorders. And also biostatistics, ethics, professionalism, communications, the healthcare systems, work on all those things. So if that's something you're interested in, just shouldn't need to or you need to or you know, just shouldn't need to through the website. And I'll give you some more information. And then I also help with applications, right? Especially like mock interviews. Um, again, just reviewing your apps, applications and things like that. I do that through through Zoom. And then again, I have a new website. I started. It's called divine intervention life lessons.com. I'm on that website, basically many people have said, Oh, divine, I love the life lessons you put at the end of your podcasts. I really wish, ah, you know, you could make more. So I'd send me a new website. It even has has a podcast attached to it. If you go on Apple podcasts and look for divine intervention life lessons podcast, you'll find it right now at 28 episodes. But basically, you know, the podcasts are around like 10 to 15 minutes long.

And I talk about some life lessons that is, you know, Bible based teaching that is relevant to our world today. And then I also have a You Tube channel, divine intervention, ah, you have a semi-lipp podcast and videos. That's where I post the videos that I make. And then in addition to that, ah, you know, have this podcast itself on Apple podcasts on Google podcasts, on Spotify, at least the most recent 150. If you want everything from the very beginning, you need to go on the website, ah, divine intervention podcast.com. That's where I also post the slides for the things I've made. And if you want notes that go with many of the, especially the step 2 CK step 3 content, there are notes for them on my website. And obviously, there's a, ah, ah, there's like a search feature and things like that that can help you navigate. And really if you subscribe to the website, divine intervention podcast.com, you'll get an email notification whenever I make a new podcast. So thank you for listening to me. I'll see you in the next podcast. God bless you. Thank you.

C3, 4, and 5.

Intercostal vein $\rightarrow$ Intercostal artery $\rightarrow$ Intercostal nerve (V-A-N).

The phrenic nerve.

The vagus nerve (CN X).

A bulge lateral to the inferior epigastric vessels, or arterial pulsations of the inferior epigastric vessels medial to a bulge.

The endothoracic fascia.

Diaphragmatic paralysis, often presenting as asymmetry of the diaphragm on chest X-ray.

The visceral layer of the seropericardium.

Overriding aorta, pulmonary stenosis, right ventricular hypertrophy, and a Ventricular Septal Defect (VSD).

Skin $\rightarrow$ Superficial fascia $\rightarrow$ External intercostals $\rightarrow$ Internal intercostals $\rightarrow$ Innermost intercostals $\rightarrow$ Endothoracic fascia $\rightarrow$ Parietal pleura $\rightarrow$ Plural cavity $\rightarrow$ Visceral pleura $\rightarrow$ Lung parenchyma.

It arises lateral to the inferior epigastric vessels.

Diaphragmatic paralysis, often presenting as asymmetry of the diaphragm on chest X-ray.

The visceral layer of the seropericardium.

Overriding aorta, pulmonary stenosis, right ventricular hypertrophy, and a Ventricular Septal Defect (VSD).

Skin $\rightarrow$ Superficial fascia $\rightarrow$ External intercostals $\rightarrow$ Internal intercostals $\rightarrow$ Innermost intercostals $\rightarrow$ Endothoracic fascia $\rightarrow$ Parietal pleura $\rightarrow$ Plural cavity $\rightarrow$ Visceral pleura $\rightarrow$ Lung parenchyma.

It arises lateral to the inferior epigastric vessels.