 Good day everybody. This is Dr. Sanjeev Sanyal, Professor of the Department Chair. This is going to be a demonstration of the muscles of the anterior abdominal wall. This is a supine cadaver. I'm standing on the right side and we shall demonstrate the muscles. So we have completely removed the skin, the superficial fascia which is the campers layer, fatty layer and we have removed the scarpas layer which is the membranous layer. What we are seeing are the muscles of the anterior abdominal wall. Let's focus on the right side. So first of all take a look at this muscle here which I'm tracing with my hand right now. This is the external oblique muscle of the abdomen and we can see that the direction of fibers are like this. They're going downwards, forwards and medially. So they are like as if the hands are in the pocket. So that is the direction of the fibers of external oblique. Now I'm going to reflect the external oblique because we have split it here and we have split it here to tell more details of the external oblique. So I am now reflecting the external oblique. This is the lower part of the external oblique that I'm reflecting and this upper part I'm reflecting here. So what do we see? We see that the external oblique, these fibers up here, they are partially inter-digitating with these muscles here. These are the ceritus anterior muscle. This eponeurosis of external oblique is also giving partial origin to the remnants of the pectoralis major that we can see here. This is the primal part of the pectoralis major. This external oblique eponeurosis also forms part of the better the breast. Having mentioned all that, what is the origin of the external oblique? It takes origin from the fifth to the twelfth ribs and the fibers, they go downwards and medially and two things happen. Number one, the infromedial fibers. They form this structure here that you can see. This is the inguana ligament which I shall mention just a little while later. And it also gets inserted onto this bony prominence that we can feel around here. It gets inserted on the outer lip of the iliac crest. Medially the fibers, they become eponeurotic and we can see the eponeurosis here. And they form the anterior layer of the rectus teeth which I shall mention later and then it continues and it becomes the part of the linea alba which also I shall mention briefly towards the end. So this is the full external oblique eponeurosis. Now let's lift up the external oblique eponeurosis again to show the next muscle underneath. Which is what I have done here. We can see this muscle here. This is the internal oblique muscle of the abdomen. First of all, we can see that the internal oblique muscle, the diagonal fibers are almost at right angles to the external oblique. The fibers are going up and medially like as if the hands are crossed to the across the opposite chest. This is the internal oblique. This internal oblique it takes origin from the middle lip of the iliac crest. Posteriorly it takes origin from eponeurosis which forms a thoracolumbar fascia. And it gets inserted onto the 10th, 11th and 12th rips. The fibers they go and then they form part of the rectus teeth and they form the linear album. The lateral half of the inguinal ligament which I mentioned just a little while back also gives origin to the fibers of the internal oblique. Now we are going to remove, we have split open the internal oblique fibers and I'm separating it from here. And I have separated the internal oblique. And we can see yet another muscle. This muscle is the transversus abdominus muscle. First of all, we notice that the rational fibers of the transversus abdominus are exactly as their name implies. The fibers are going transversely. So therefore, this is the transversus abdominus. What is the origin insertion? The transversus abdominus muscle takes origin from the 7th through the 12th rips posteriorly. It also takes origin from the posterior eponeurosis which forms a thoracolumbar fascia. Down below it takes origin from the inner lip of the iliac wrist. And the fibers they go medially and they get inserted onto the zippered process, the linear album and the pubic wrist. It also helps to form the posterior layer of rectus teeth. So this is the transversus abdominus. And we can notice that between the internal oblique and the transversus abdominus, we can see this neurovascular bundle. This is the neurovascular plane between layers number two and three. This in all probability is the subcostal nerve because I can feel the 12th rib here. We shall come to that just a little while later. What are the actions of these muscles? These flat muscles of the abdomen, they are the antrilateral muscles of the abdominal wall. They had to maintain the intracerminal pressure. They are responsible for contralateral torsion of the trunk. They had to hold the abdominal contents in place. So these are some basic functions of the flat muscles of the abdomen. That brings me to this lower portion of the external oblique which I mentioned in the beginning. And we can see that this is the aponeurosis of the external oblique which has become thin, shiny and ligamentous. It forms a structure here which extends from the anterior superior iliac spine where my index finger is located and goes medially where my finger has disappeared. This is the pubic tubercle. So this is the full extent of the attachment of the inferior fibres of the aponeurosis. This is the inguinal ligament. This inguinal ligament has got several components. Number one, the main inguinal ligament itself. Then it has got an upturned portion like my head is showing. That portion is called the pupar's ligament which forms the part of the floor of the inguinal canal which I shall mention just now. Then it gives a small reflection upwards and medially which is called the reflected inguinal ligament which we cannot see here which forms part of the posterior wall of the inguinal canal. And it also forms a curved structure which is called the lacrynal ligament which forms part of the floor of the inguinal canal. So these are the four expansions of the inguinal ligament. We have split the inguinal canal. This is the aponeurosis of the external oblique. And this forceps is holding the two ends together to show you the location of what is called the external inguinal ring. This is the external inguinal ring. So I have kept it together just to show you the location of the external inguinal ring. Now I am going to separate which I have done. I have separated the leaves of the external oblique. This is the inguinal canal. And we can see running through the inguinal canal is this structure here. These are the structures of the spomatic cord which are passing through the external inguinal ring. And they are continuing into the scrotum because this is the main cadaver. At the external inguinal ring it has got two crura. A medial crust and a lateral crust. The medial crust merges with the rectus sheath. The lateral crust gets attached to the pubic tubercle. And in between there are intercrual fibres which we have removed. That is the external ring. Now let us take a look at this structure here. This curved muscular structure that we can see. And I have lifted it up here so that we can see it better. This is what is known as the conjoined muscle and the conjoined tendon. And we can see the fibres are starting from here. They are arching over and they are going posteriorly. This combined muscle is actually called the conjoined muscle conjoined tendon. It is a combination of two muscles. The transversus abdominis and the internal oblique. The two together forms this bundle here. This conjoined muscle starts from the origin of these two muscles. The transversus abdominis and internal oblique from the inguinal ligament. It forms the roof of the inguinal canal. And then it forms part of the posterior part of the inguinal canal and then gets attached to the pectinial line of the pubis. So this is the fibro-apodionotic arch of the inguinal canal that we can see here. The next structure in the inguinal canal that we can see here is this one here. This is the ilio-inguinal nerve which comes from here and I will show you the neurovascular structures. So that brings me to the concept of myopectinial orifice and brine hernias. What is this myopectinial orifice? It is a concept which has been proposed by a French surgeon called Fruchot. He has said that the myopectinial orifice is the basis of all brine hernias. Anteriorly, it is bounded by this portion here. This is the conjoined muscle and the rectus abdominis muscle which you cannot see in this dissection. Posteriorly and inferiorly, it is bounded by the fascia over the iliosuas and the fascia over the pectinias. And this region is bisected by the inguinal ligament. Arising from below this inguinal ligament is this opening here where my instrument is located. This is the femoral canal which gives origin to the femoral hernia especially in females. Femoral hernia is more common in females because the femoral vein is smaller and the pelvis is wider in females. Above this inguinal ligament is this inguinal canal where my instrument is busing right now. This is the site of inguinal hernia which goes like this and then it passes from external rate and then it goes into the scrotum. This is the indirect inguinal hernia. So Fruchot has proposed that the myopectinial orifice is the basis of all brine hernias. Above the inguinal ligament is the inguinal canal, inguinal hernia and below the inguinal ligament is the femoral canal, the femoral hernias. Now let me show you again the neurovascular structures. So I have again come back to my initial section and I have separated out the internal oblique and the transverse abdominus. So we can see that this layer between the internal oblique and transverse abdominus is the neurovascular plane and we can see one prominent nerve passing here. This is the subcostal nerve and this abdominal muscles are supplied by the thoracoabdominal nerves namely T7A91011 subcostal nerve and the lower portion is supplied by the ilioinguinal and iliohypogastric. In order to see the ilioinguinal and iliohypogastric we shall come under here. I have lifted up the internal oblique and we can see this nerve going. This is L1. This ilioinguinal and iliohypogastric they supply the lower fibers of the internal oblique and the transverse abdominus. Iliohypogastric does not go below the abdomen. The ilioinguinal continues through the inguinal canal and it supplies the skin of the upper medial thigh and the anterior scrotum where it's called anterior scrotum nerve or in the females the anterior labial nerve. So this also supplies the lower part of the abdominal wall muscles only the internal oblique and the transverse abdominus. So this is the neurovascular plane. Let's come to the medial portion of this. We can see this thin structure. It is not so thin as it looks. It is a very tough structure and this is a cut margin. This is the linear alba. The linear alba is the place where we have criss-crossing of fibers from both the sides and we can see the fibers here the shiny white fibers. At the linear alba we have what is known as inter muscular exchange of fibers and intra muscular exchange of fibers. What is this? The superficial fibers of the external oblique of one side they criss-cross to the opposite side and they merge with the deep fibers of the external oblique of the opposite side and vice versa. That is called intra muscular exchange of fibers. Not only that the fibers of the internal oblique of one side they also cross the linear alba and they merge with the external oblique muscle fibers of the opposite side that is called inter muscular exchange of fibers. So when fibers from both the sides cross over they form a tough structure here that is called the linear alba and we can see the cut margin of the linear alba here and we can see the cut margin of the linear alba here. It's a very tough structure. Linear means line. Alba means white. This is the umbilicus incidentally. This linear alba is surgically very important. When we have want quick access to the end domino like for example, predniges or intra abdominal bleeding where we don't have time to waste we enter through the linear alba. It gives us access to the intra abdominal contents within seconds. The point to be remembered is when we are repairing closing the intra abdominal war after surgery we have to close the linear alba by means of non-absorbable sutures. Usually I prefer nylon loop. If we use absorbable sutures then we are likely to see recurrence of hernia which is called incisional hernia and I have seen several such cases in my clinical practice. So the linear alba has got disadvantages and disadvantages. So that's all for now that I wanted to show you. Dr. Sajya Saryan signing out. Vajpadel is the camera person. If you have any questions or comments please put them in the comment section below. Stay tuned for the next video. Please like and subscribe. Have a nice day.