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OK, we've got seven people so far. I mean, it's a decent amount. Um I've turned the recording so um we can upload this to I afterwards. So, hi. Hi everyone. Welcome to the er Surgical Anatomy MRC S uh revision part two. We have lovely doc Mr Azim joining us again today. Um So similar housekeeping rules. So, um it's up to you if you want to turn your camera on and off, I'll add everyone to the stage so everyone can turn on their microphones if they want to answer any questions or ask questions at the end. Um But for if you're not, um for the time being, if you could keep your microphones turned off just so we don't get any noise disturbance throughout the talk if you have any questions, um we can try and leave them ideally till the end just so we don't disturb the flow and we can finish on time. Um And uh but you know, if Mister Azim asks questions throughout neck, feel free to answer his questions and turn on the mic. OK. All right. Thank you. I'll leave it to you, Mister Razin. OK. Thank you. And uh welcome everyone. So, uh we just make a start. Uh I mentioned yesterday uh uh I just repeat to those who are due uh to this uh session that it's very difficult to cover each and every topic in uh anatomy. So I'm just uh just touching base to the few important topics that uh are repeatedly uh asking the in the exam. Yes. So, uh it's, it's just a framework actually. So I will hopefully will help you guys to uh to read further. So, uh the first one, so we yesterday we we started from head and to uh covered the head, neck, thorax, and diaphragm. So uh moving forward. So abdominal wall is a very important question about the uh about the rectus sheath and how the muscles are arranged to uh in the re in the rectus sheath. So as you all know, uh if you look at the left side of the diaphragm, so the the the four main four main muscles that make the anterior abdominal wall. So we are coming from lateral and moving towards the midline. So from laterally, we have three main muscles as the name indicates external oblique, internal oblique, and transversus abdominis from outside inwards. And as we move towards the midline, towards the midline, so midline is the median Rae in which these muscle tendons are inserted as we know there's no bone. So this is the the strongest structure or the rope like structure in which these muscle tendons are inserted. But in their way, there is another muscle that's, we call it a six pack muscle or Rectus Abdominis muscle. So the whole game is how these three muscle tendons are arranged around the Rectus Abdominus muscle. That's the whole actually game here. So if you come back to the left side of the diagram again, so the external oblique uh muscle ep puros as it's the most superficial, it's always on the, on the top of the rectus abdominis muscle. While the internal oblique muscle tendon, it splits into two and one of the layer goes anteriorly and fuses with external oblique ep inurois. While the other layer goes inferior to the rectus abdominis and fuses with the tendon of the transversus abdominis and this sandwich, the transversus ab uh sorry rectus abdominis muscle all around. And then they become a one unit that's inserted into this midline and uh ra that's called linea alba. So this is the arrangement from Z sternum all the way down, few centimeters below the umbilicus. But what happens below the umbilicus is few centimeters below you where this uh shaded gray line starts. This is the arrangement here. So what happens is uh as we said, external oblique, always outside, but internal oblique muscle instead of splitting into two remains one unit and passes anteriorly. And the transversus abdominis muscle tendon also joins the internal oblique and they both fuse together and passes anterior to the rectus abdominis. So the all three muscle tendons are passing anterior to the rectus abdominis at this level. So this area and what this causes is it causes AAA gap at the edge of the rectus abdominis muscle. And it's called, it's called arcuate line. So this shaded area is basically called a Spigelian belt. And I'm sure you guys have heard of uh Spigelian hernia. That's where the, this is the area where the spigelian hernia usually originates. I mean, ii know they have, they have labeled this whole area as a Spigelian belt. But most of the time you will see spigelian hernia arising from the arcuate line and mostly they arise on the left side. There is no specific reasoning given why we, we don't see spigelian hernia on the right side, but mostly you will see in clinical cases they arise from the left side. So this is very important question about the rectus sheath and how the muscles are uh and their tendons are arranged around the rectus abdominis muscle moving forward. Uh We let's talk about the liver. And uh other important question is about how the liver is divided into different segments. The classification use is called the key not classification. And there are two main structure that divides the liver into eight segments. One is the hepatic vein that's coming from the are going to the inferior vena cava. And the other structure is the portal vein. So you can see the portal vein is dividing is go is going horizontally and dividing uh the liver into segments. While the hepatic veins are coming from above and dividing the segments into right into, into medial or lateral. So let's move uh from the left side. So the left side, you will see that the far left edge of the liver, it's divided into a segment two and segment three. You can ask where the segment one is actually here, it's called coordinate lobe there. A segment two top is the segment two inferior to that is segment three and they are divided by the branch of the portal vein. You can see so horizontally is the portal vein. Vertically are the hepatic veins medial to it is the segment four. Sometimes you will see it's labeled as four A four B but it's a one whole unit then comes the. So, so these are divided by the left hepatic vein, then comes the medial uh middle hepatic vein dividing the four from five and eight. So you will see how the the flow of the segments of of flows here is 567 and eight. And if you vi visualize in your mind, six and eight is basically turned posteriorly. So the whole liver is not like a flat like this. It's basically 2345 and eight are on the, on the anterior and the six and seven are posteriorly. So the right hepatic vein divides the right side of the liver into anterior and posterior. If it makes sense on the l on the left side, it divides into lateral and medial. I hope you guys are with me. And further division between five and eight, six and seven is by the branch of the portal vein. So this is further clarified here. Excuse me. And where is the central line? It's not the falciform ligament that's very falsely uh interpreted. And when we see intraoperatively falciform ligament attaching to the kind of a middle of the liver. Falciform ligament is not dividing the liver into right and left is this line called the the canal line basically is where the middle hepatic vein is. So the right side of the liver is 23 and four, sorry left side of the liver is 23 and four segments, right.