 Welcome to the section of the anterior abdominal wall structures and Dr. Sanju Sanyal, Professor Department Chair. This muscle is the external oblique muscle of the abdomen. The direction of fibers of the external oblique muscle are downwards as if the hands are in the pocket. External oblique muscle is also covered by its own deep fascia and that is this one here. Every flat muscle of the abdomen has got its own deep fascia. Once we reflect the external oblique muscle, we see the next muscle underneath and that is the internal oblique muscle. The internal oblique muscle fibers are directed exactly opposite to the direction of the external oblique muscle and they are inserted onto the 10th to the 12th ribs. Now let me reflect the internal oblique muscle. We see the third layer of muscle and that is horizontal fibers. This is the transversus abdominis. The layer between the internal oblique and the transversus abdominis is the vascular layer where all the vascular structures travel. These muscles are supplied by the thorac abdominal nerves namely T7, 8, 9, 10, 11 and also supplied by L1, ilioenguinal and iliohypogastric which all travel like this and they supply the muscles of the abdomen. The flat muscles maintain the internal abdominal pressure holding abdominal contents and also push the trunk to the opposite side. External oblique muscle, internal oblique and the transversus abdominis muscle as they travel anteriorly they become aponeurotic and we can see that the anterior parts of all these muscles are aponeurotic and these aponeurotic muscle fibers they split to form rectus sheath. Additionally the external oblique muscle anterior part of it forms this structure here and I put my finger here this is the inguinal ligament which stretches from the anterior superior iliac spine to the pubic tubercle. Now I am going to show these same muscles from the opposite side. Now we are showing the same flat muscles of the abdomen from the opposite side from a different perspective. This muscle that we have reflected up this is the external oblique muscle. This is covered by its own deep fascia and the anterior part of the muscle is aponeurotic and you can see the directional fibers are as if the hands are in the pocket. Once I reflect this we see the next muscle and that is the internal oblique which also covered by its own deep fascia and the directional fibers are as if the hands are in the opposite chest and again the anterior part of this muscle has become aponeurotic and once we lift up this we see the third layer of muscle and that is the transversus abdominis and we also notice that the external oblique aponeurosis and part of the internal oblique they constitute the anterior layer of the rectus sheath while the posterior layer of the internal oblique and the transversus abdominis constitute the posterior layer of the rectus sheath. This is the lower part of the external oblique aponeurosis and we can see it is ending in this ligament the structure here. If I put my finger here you will notice that this is a tough ligament the structure. It extends from the anterior superior elixpine and it ends at the pubic tubercles and this structure is the inguinal ligament. Just to bring you up to speed this is the dissection of the lower limb and we can see that the fascia let of the thigh remnant of which is seen here is inserted onto the inguinal ligament and we have split open the lower part of the external oblique aponeurosis and when we put our finger here we notice that the lower part of the inguinal ligament has got an upturn lower margin and that is called the poo part ligament and that is where my finger is located which is actually an extension of the inguinal ligament and when we split open this lower part of the external oblique we have entered into the inguinal canal. Now this is a female cadaver so therefore we do not see the usual contents of the inguinal canal however we can see a few other structures. This is the remnant of the round ligament of the uterus which comes from the uterus it goes through the internal ring and it goes down and it gets merged with the subcutaneous tissue of the labia majora. We can see these curved muscle fibers here which are starting from here and going over and going to the other side. This is what conjoined tendon or the fax inguinalis. This conjoined tendon is actually the fused lower fibers of the internal oblique and the transverse abdominis and they form groove and the posterior wall of the inguinal canal. Now we shall go again to the opposite side to see some more constant contents of the inguinal canal. So now we have come to the opposite side to show again the inguinal ligament. So my finger is on the inner surface of the inguinal ligament namely the popart ligament which is the inferior curved portion and we can see it very clearly here. This is the inguinal ligament and the curved portion of that is the popart ligament and it extends from the anterior superior elixpine which is here to the pubic tubercle which is here and we have again split it open to show the interior that is the inguinal canal which is a common site of inguinal hernia in maize but we can see a few other structures which we could not see on the other side. First of all we see this nerve here. This is the ilio-inguinal nerve and the ilio-inguinal nerve is the one which supplies the internal oblique and the transverse abdominis muscle and it supplies the upper medial thigh and the anterior labia majora and scrotum so called anterior scrotum or anterior labial nerve and it plays a role in the afferent of the cremasteric reflex. You can see some of the fibers of the conjoined muscle. We see the next nerve which is traveling inside the inguinal canal. This is the genitofemoral nerve as the term implies genital and the femoral. The femoral branch supplies the anterior part of the upper part of the thigh and the genital part supplies the anterolateral scrotum and the labia majora and it also supplies the cremaster muscle in the males and it serves as the efferent arm of the cremaster reflex. We have pair of hernias which are common in males and females respectively namely the inguinal hernia in males and the femoral hernia in females. That brings me to the concept what is known as the myo pectinial or a fist concept which has been postulated by a friend gentleman known as Frushroth. This is an area founded by posteriori by the iliosoas muscle, the pectinus muscle and the respective fascia and superiorly it is bounded by the muscles of the conjoined tendon and the rectus abdominis in the rectus teeth and this myo pectinial or a fist is bisected by the inguinal ligament. Below in this region we have the femoral canal where my instrument has gone in and this is the site of femoral hernia in females which is medial to the femoral vein and above the upper part of the myo pectinial or a fist which we have opened up this is the region of the inguinal canal which is the site of inguinal hernia in males. So this is the concept of myo pectinial or a fist which forms the basis of all groin hernias. Now I shall reflect the layers of the rectus teeth here. So this is the anterior layer of the rectus teeth which we mentioned is formed by the fusion of the external oblique eponeurosis and the anterior half of the internal oblique and once we lift up the anterior layer of the rectus teeth we can see the muscle which is underneath and that is the rectus abdominis muscle and once we reflect rectus abdominis muscle we see the posterior layer of the rectus sheath and this is formed by the transverse abdominis eponeurosis and the posterior half of the internal oblique running inside the posterior rectus sheath we can see these blood vessels this is the inferior epigastric vessels and coming from the top of the superior epigastric vessels so they run between the rectus abdominis muscle and the posterior layer of the rectus sheath and the anastomose here. The upper three-fourths of the rectus sheath is composed of the structures which I mentioned but the lower one-fourth of the rectus sheath is composed of only the fascia transversalis and the parietal peritoneum and the junction between the two is called the arcuate line. Above this is the full layer of the posterior layer of the rectus sheath and below this the rectus sheath is deficient and it is through this that the inferior epigastric vessel passes into the posterior rectus sheath. The same thing we can see on this side this is the parietal peritoneum and the layer here this is the fascia transversalis so running between the fascia transversalis and the parietal peritoneum we have the inferior epigastric vessel running and the inferior epigastric vessel enters the rectus sheath at the arcuate line which we can see here also we can see this curved line here this is the arcuate line above this the posterior rectus sheath is complete and below this the posterior rectus sheath is deficient and it is composed only of the fascia transversalis and the parietal peritoneum. So these are the structures which I wanted to show you in the anti-abdominal wall thank you very much for watching ladies and gentlemen have a nice day Dr. Sanjay Sanyal signing out if you have any questions or comments please put them in the comment section below. Hey guys please subscribe and make sure you like this video