 This is a supine can ever we are demonstrating the abdominal wall. I'm standing on the right side camera person is also on the right side So this structure that we see in front of us This is the anterior layer of rectus sheath on the right side and this is the anterior layer of rectus sheath on the left side How's the anterior layer of rectus sheath formed? It is formed by the union of the aponeurosis of the external oblique muscle of the abdomen, which is this muscle and The anterior leaf of the internal oblique muscle of the abdomen, which is this muscle here These two views to form the anterior rectus sheath which covers the rectus muscle from front and that is what is seen in both the sides Then there's a posterior rectus sheath, which I'll show you just now and that posterior rectus sheath is formed by the posterior leaf of the internal oblique muscle and The aponeurosis of the transverse abdominis muscle, which is seen here have split open the rectus sheath So I'm reflecting the anterior rectus sheath on the right side and this other leaf and we can see the muscle inside This is the rectus abdominis muscle. We will do the same thing on the other side Also, I'm reflecting the anterior layer of rectus sheath on the left side and we can see the rectus abdominis muscle here The rectus abdominis muscle is a very long muscle and as the term implies rectus means straight It is the most powerful muscle of the abdomen It takes its origin the proximal attachment from the pubic sephisis where my fingers located and the pubic rest on each side And the muscle then goes up and it fans out slightly and then it gets inserted onto the fifth to the seventh costal cartilages So therefore at the placement it gets inserted There is no posterior layer of rectus sheath because the costal cartilages themselves form the equivalent of the posterior layer Only the anterior layer is present. This rectus abdominis muscle has got multiple tendinous intersections And we can see in this particular cadaver at least four of them One tendinous intersection is usually at the costal margin and we can see that here Then there's another one here The third one is approximately at the level of the umbilicus that is here and there can be a fourth one and we can see it here These tendinous intersections break up the action of the long rectus muscle into multiple sections And therefore each of these sections can act independently Because the nerve supply to the muscle is segmental which I should show you just now We would have heard of the term six pack of domain The rule of thumb is the number of tendinous intersections Multiplied by two gives the number of packs of the domain. So this particular cadaver during life Could have had an eight pack of domain some people who have four pack of domain some people have even ten pack of domain What are the action of this rectus abdominis muscle? It is useful for increasing the intra-abdominal pressure. It is used for sitting up from a lying position Therefore people who do abdominal crunches they develop this muscle And that is how they develop the packs because this muscle gets hypertrophied and the tendinous intersection is a place where the Muscle is attached to the skin. So therefore it produces the so-called packs. It is useful to flex the lumbar spine So therefore it is an anti-lordotic muscle and because it is inserted out of the costal cartilages It also acts as an accessory muscle of respiration during forced exhalation like for example an M5C man The rectus abdominis muscle comes into play and it's a very powerful muscle And this is the muscle which boxers use to develop to protect their abdomen when they are boxing now what we have done We have cut the rectus abdominis muscle on the right side in its upper portion to reflect it And that's what we are doing now And this is the lower part of the rectus abdominis muscle on the right side by so do we we have demonstrated two things One I will draw your attention to this blood vessel, which is coming from the thorax This is the superior epigastric artery It is one of the terminal divisions of the internal thoracic or the internal mammary artery Which passes through the antrolateral hiatus in the diaphragm and it comes in the rectus sheath And it supplies the posterior surface of the rectus abdominis muscle and this anastomus is with the inferior Epigastric artery which I shall show you on the other side and it is accompanied by its venaecomitantes The venaecomitantes are the veins accompanying the superior epigastric artery This venaecomitantes they form the internal thoracic vein Which they drain into the brachiosophallic vein the next structure which I would like to draw your attention to these Nerves piercing the posterior layer of rectus sheath. We can see one here We can see another one here. We can see one more here Here and here These are the thoracoabdominal nerves They pierce the posterior rectus sheath and they supply the rectus abdominis muscle in a segmental fashion That's why I mentioned that if we do cut the rectus abdominis muscle in one place The other portion still continues to function because the nerve supply is segmental The thoracoabdominal nerves are 7, 8, 9, 10, 11 and the 12th one is called the subcostal nerve Above the umbilicus is 7, 8, 9 at the level of umbilicus is T10 and below the umbilicus is 11 and 12 In this we can see the posterior layer of rectus sheath But the details of that I shall describe on the other side So now we have come to the left side of the abdomen and I'm narrating from the left side and the camera person Is also on the left side So we have reflected the left anterior rectus sheath and we can see the left rectus abdominis muscle And here we have cut it in the lower portion The reason for doing it is because certain structures are visible more on the lower part of this side And when I reflect the lower part of the rectus on the left side, we can see this blood vessel This is the inferior epigastric artery and we can see that it's accompanied by the inferior epigastric vein Which drains into the external iliac vein inferior epigastric artery as it rises from the external iliac artery It runs behind the fascia transversalis and this is the fascia transversalis, which I have Lifted up here Here it runs on the posterior wall of the inguinal canal Just medial to the internal ring of the inguinal canal And then it enters the rectus sheath now. I'm going to turn back this muscle To show my finger inside the inguinal canal on the left side So my finger is now in the inguinal canal And we can see my finger has come here So this is the path that the inferior epigastric artery takes And this is the cut portion of the fascia transversalis, which is the posterior wall of the inguinal canal While we're talking of the fascia transversalis and the posterior wall of the inguinal canal Now is the right time to show you another very important landmark that we can see in the posterior wall of the Rectus sheath I have stretched out the posterior wall of the rectus sheath And as I mentioned posterior wall of the rectus sheath is formed by the half the aponeurosis of the internal oblique And the full aponeurosis of the transversal abdominis This rule applies only to the upper three folds of the posterior rectus sheath The lower one-fourth of the posterior rectus sheath is formed only by the fascia transversalis, which I have again picked up here And the junction between the lower one-fourth and the upper three-fourths Is visible here and we can see a line We can see that this is the line. This is the called the archaoid line This line demarcates the upper three-fourths and the lower one-fourths So therefore technically speaking the lower one-fourth does not have a true proper posterior wall of the rectus sheath It is formed only by the fascia transversalis And this archaoid line gives space for the passage of the inferior epigastric artery into the posterior wall of the rectus sheath This inferior epigastric artery anastomosis with the superior epigastric artery, which I showed you on the right side By the same argument inferior epigastric vein anastomosis with the superior epigastric vein And therefore this provides a site of communication between The tributaries of the superior vena cava with the tributaries of the inferior vena cava This lateral wall of the rectus abdominis muscle It forms a groove on the surface of the abdomen, which we can see in a thin walled person thin individual or A muscular person and that groove is referred to as the linia semilunaris Rarely we can have a hernia coming out through the linia semilunaris And that hernia is referred to as a spigelian hernia Since we are already on the anterior rectus sheath on both the sides, which I have lifted up here We can see that the two anterior layers of rectus sheath and the posterior layers of rectus sheath They all merge in this central midline structure and I have lifted it up here This midline central structure is called the linia alba linia alba as the term implies It's a white line and this is a very tough structure It contains criss-crossing fibers From the external oblique muscle of one side to the deep fibers of external oblique of the opposite side and vice versa And it also contains criss-crossing fibers from external oblique of one side to the internal oblique of the other side And this criss-crossing fibers are referred to as the intramuscular interchanger fibers And because of this criss-crossing of fibers the linia alba constitutes a very strong tough Fibrous structure, which gives protection to the abdomen Sometimes we can have a defect in the upper part of the linia alba And that is known as dive irrigation of recti and that can be demonstrated When we ask the patient to on a like patient to lift up the head From the bed without using the hands we can see a bulge and that is referred to as dive irrigation of recti The umbilicus is a weakness in the linia alba through which the umbilical cord came out in fetal life When the umbilical cord drops off it forms a psychiatric In children, in babies, it can be a site of an umbilical hernia But 93% of them close by one year of age It requires surgery only if it does not close after one year of age In adults, we do not get umbilical hernia Instead we have what is known as a para-umbilical hernia Where it is located on either one side or the other side of the umbilicus And finally to conclude we can see this is the inguinal canal on the left side Which can be a site of inguinal hernia And we can see these fibers here, these are the conjoined tendon muscle fibers Which are composed of the fused fibers of the internal oblique and the transverse abdominis And we can see the spermatic cord is passing through the external ring In this particular cadaver we had some interesting situation We can see some remnants of suture material here They had done an extensive surgery in the lower part of the linea alba And they had implanted this structure that we can see here This is a reservoir which they had implanted in the left rectus sheath And this is the place where it was located And from this reservoir we can see a pipe coming out This tube is going inside the strotum And we can see another pipe coming out from the strotum And it is coming and continuing This is a 3-P spiral implant for urinary incontinence An artificial urethral sphincter For this region this whole lower portion was density, adherent and fibroids And that's why we could not see many of the structures on the right side And we came to the left side So these are the structures which I wanted to show to you In the abdominal wall put it into the rectus sheath The neurovascular structures and the rectus abdominis muscle Thank you very much for watching Dr. Sanjeev Sanyal signing out Please like and subscribe If you have any questions or comments Please put them in the comment section below Have a nice day