 This is going to be demonstration of the muscles of the posterior abdominal wall. So, we have removed all the structures here. This is supine cadaver. This is the left side. I am standing on the right side. The camera person is on the left side. So, let us take a look at the muscles of the posterior abdominal wall. Straight away we can see this muscle here in front of us. This is the medial part of the posterior abdominal wall and this is the suas major and the suas minor. So, we have lifted up the suas minor separately. The suas minor takes origin from T12 and continues down and it forms the iliopectinial arch. It gets attached to the iliopubic eminence and it gets attached to the inguinal ligament through the iliopectinial arch and thereby it converts the sub-inguinal space into a medial vascular compartment and a lateral muscular compartment. Then we have this suas major muscle. This takes origin from T12, L12, 3, 4, 5 and it continues down and it merges with the tendon of the iliacus muscle that we can see here arising from the inner surface of the iliac fossa. The iliacus muscle is the one which is occupying the inner surface of the iliac fossa here and it merges with the tendon of the suas major and the two together from the ilio suas tendon. Rest of the ilio suas tendon I shall show you on the right side and it gets inserted onto the lesser trochanter of the femur. The function of the suas major alone when it acts on one side it was lateral flexion of the lumbar spine. When a person is sitting and both the sides are acting together then it causes flexion of the lumbar spine. It is also referred to as the lordotic muscle. It contributes to the formation of the lumbar lordosis and indirectly the formation of the thoracic typhosis and when it is combined with the iliacus the ilio suas tendon they together act to flex the head. So that is about the action of the ilio suas. If there is a rupture of the tendon of the ilio suas at its insertion to the lesser trochanter then the person will be asked to elevate the thigh from the bed. The person will have pain and tenderness and that is called lute lobsign. The suas muscle is covered by a sheath which is called the suas sheath which is actually the medial continuation of the posterior real fascia or the fascia transversalis. In case of ostomalitis of the lumbar spine pus can track down under the suas sheath and it can continue down and that is referred to as the suas abscess. The suas abscess cannot go down below the iliacus trochanter. This is the transversity scan of the abdomen to show a right suas sheath abscess. In cases of pelvic appendicitis which is on the right side the suas muscle can be irritated and that can lead to suas spasm and the patient will have flexion of the hip and that is referred to as the suas sign or the zacary corp sign and when we try to passively extend the hip the patient has pain and that is known as suas test of the zacary corp test. So these are some important clinical correlations pertaining to the suas measure and the iliacus. The next muscle that we can see at the posterior lumbar wall is this one here. This is the quadratus lumborum. The quadratus lumborum takes origin from the ilio lumbar ligament which we can see here and it also the various slips of the lumbar vertebrae and it gets inserted onto the 12th rib. This is also covered by a fascia called the quadratus fascia which we have removed and that is the anterior layer of the thoracolumbar fascia. This quadratus lumborum when it acts on one side it again causes lateral flexion of the lumbar spine but when it acts on both the sides then it causes extension of the lumbar spine which is opposite to that of the action of the suas measure and by virtue of the fact that this is inserted onto the 12th rib it also acts as an accessory muscle of respiration. It assists the diaphragm during forced inspiration and also fixes the rib in forced expiration for example in emphysema or during exercise or heavy breathing. On the left iliacus muscle we can see an arterial anastomosis. This arterial anastomosis is formed by contributions from three arteries. The first artery that we have picked up here this is the fourth lumbar artery on the left side. The next artery that contributes to this anastomosis is this one. This is the branches of the iliolumbar artery which comes from the posterior division of the internal iliac artery and the next artery which contributes to this anastomosis is this artery here. This is the deep circumflex iliac artery which comes from the external iliac artery that we can see just in front of that. Now let me mention a few quick words about the sheath of these two muscles. Quadratus lumborum sheath and the suas major sheath. The upper limit of the sheath of the quadratus lumborum forms this ligament here which is referred to as the lateral archivate ligament which provides attachment to the diaphragm. Likewise the upper limit of the suas major sheath also forms a ligament which is called the medial archivate ligament which also provides attachment to the diaphragm. So these are the muscles of the osteo abdominal bone that we can see here with their respective functions and the clinical correlations. Now we should show the same muscles on the right side. Now we are on the right side of the abdomen. I'm narrating from the right side and the camera person is also on the right side towards the leg end. So this is the suas major muscle. Here we cannot see the suas minor muscle. Next this is the muscle that we can see this is the iliacus muscle and we can see that the tendon of the suas major and the iliacus they form the ilio suas tendon and we shall trace the ilio suas tendon on the thigh because we have opened the thigh on this side and this combined tendon that we can see here which is just lateral to the femoral nerve this is the ilio suas tendon and my finger is going right down to its insertion onto the crucial canton. So this is the ilio suas. So therefore when this contracts it is a flexion of the hip. Injury to this muscle or rupture of this muscle will produce pain and tenderness on attempted hip flexion and that is known as glute lobsign. This muscle that we can see here this is the quadratus lumborum and here also we can see it is taking origin from the ilio lumbar ligament and it goes up and gets inserted onto the 12th rib here which is in this location this is the 12th rib and we have also removed the quadratus fascia and the suas sheath but we can see the upper limit which is the lateral archivate ligament of the quadratus lumborum fascia and the upper limit of the suas sheath is the medial archivate ligament both of which are giving attachment to the diaphragm. So these are the posterior abdominal wall muscles that we can see on the right side. Thank you very much for watching. Dr. Sanjay Sanyas signing out. David O is the camera person. Have a nice day.