 This is supine cadaver. I am standing on the right side. Camera person is on the left side. This is going to be a demonstration of the branches of the lumbar plexus. First I will show it on the right side. So we have removed all the structures from the posterior pneminal wall and we can see this nerve here and this nerve here. This is the iliohypogastric L1 and this is the ilioinguinal also L1. This is the beginning of the lumbar plexus. The iliohypogastric supplies the lower part of the inert two muscles of the abdomen, namely the internal oblique and the transverse abdominis. It does not go below the inguinal ligament. The ilioinguinal also supplies the lower part of these two muscles but it continues below the inguinal ligament and it supplies the skin of the upper medial thigh and it also supplies the anterior part of the scrotum or the labia majora where it is known as the anterior scrotal nerve and the anterior labial nerve in the case of females. This travels through the inguinal canal to go to the inguinal region and to the scrotum. This ilioinguinal nerve by virtue of its supply of the thigh it serves as the afferent limb of the scrimaster reflex in males. The next nerve that we see this one here in front of the suas major muscle. This is the genital femoral nerve. The name implies it has got two components a genital component and a femoral component. This is L12. Genital component goes through the inguinal canal. It goes through the spermatic cord and it supplies the cromaster muscle in the males and it also supplies the antrolateral part of the scrotum in males and the antrolateral part of the labia majora in females. The femoral component supplies the skin of the upper part of the anterior thigh. That's why it is called genital femoral. This genital femoral nerve serves as the afferent limb of the cromaster reflex in males because it supplies the cromaster muscle in the scrotum and therefore when the upper medial thigh is stroked it produces elevation of the testis towards the inguinal canal. So therefore to recap the ilioinguinal is the afferent limb. The genital femoral is the efferent limb of the cromaster reflex. The next nerve of the lumbosacral plexus is this one here. This is the lateral femoral cutaneous nerve. It comes out from the lateral margin of the suas major. It crosses the iliacus muscle and it goes under the inguinal ligament on its lateral part near its attachment to the anterior superior iliac spine. And if you were to keep on looking at this nerve I will pull the nerve below the inguinal ligament and we will see it moving. When I pull here we can see it is moving. So this is the other end of that nerve. Here under the inguinal ligament it becomes known as the lateral femoral cutaneous nerve and it supplies the skin of the antrolateral thigh by means of multiple branches as we can see here. Here again we have an important clinical correlation. When a person gains weight rapidly this nerve can get entrapped under the inguinal ligament close to the anterior superior iliac spine. Especially because the sartorius muscle also takes origin from the ASIS and this entrapment syndrome produces numbness, tingling and peristhesia on the antrolateral aspect of the thigh and that condition is known as meralgia peristhetica. Coming to the next nerve of the lumbar plexus we have this one here. This is the femoral nerve L234 lumbar plexus posterior division. Incidentally the lateral femoral cutaneous nerve is also L23 posterior division. These are the only two branches of the lumbar plexus which arise from the posterior division. This continues under the inguinal ligament through the muscular compartment of the subinguinal space and in the thigh it supplies all the muscles of the anterior compartment of the thigh as well as the large portion of the skin of the anterior thigh. Now here again if you keep looking at this nerve I am going to give traction to this nerve from the thigh and we will see it moving here. So I am pulling the femoral nerve here. This is the femoral nerve in the thigh. The moment it enters the thigh it immediately breaks up into hundreds of branches which supplies all the muscles of the anterior compartment. So this is the femoral nerve. Coming to the next nerve of the lumbar plexus is this nerve here which I have picked up. This is the obturator nerve. This is also L234 but from the anterior division of the lumbar plexus. This runs medial to the suvash major muscle and it goes into the pelvis and then it runs in the lateral wall of the pelvis and then it goes through the obturator canal and it comes to the thigh which we cannot see in this particular dissection and it supplies all the muscles of the medial compartment, the adductor compartment of the thigh and also supplies the skin of the middle medial one third of the thigh. This is the obturator nerve. The next nerve of the lumbar plexus is this nerve which I have picked up just medial to the obturator nerve also deep inside the pelvis, this one. This is the lumbosacral trunk L45. This lumbosacral trunk is the contribution from the lumbar plexus which goes to the sacral plexus and contributes to the formation of the sciatic nerve which root value is L45S123. Therefore to recap the branches of the lumbar plexus are iliohypogastric, ilioenguinal, genital femoral, lateral femoral cutaneous nerve, obturator nerve, femoral nerve, lumbosacral trunk. Just to recap I'm going to show the same nerves on the left side of the cadaver. So this is the left side of the abdomen and we can see the iliohypogastric and the ilioenguinal nerves here. The iliohypogastric and the ilioenguinal. We cannot see the genital femoral nerve. We can see the lateral femoral cutaneous nerve. We can see the femoral nerve here. This is the femoral nerve but we cannot show it on the thigh because this side the thigh has not been dissected out. Coming on the medial side we can see this is the obturator nerve. This is the lumbosacral trunk which I have picked up L45 which goes to the sacral plexus and forms the sciatic nerve. Before I conclude let me mention few clinical correlations. There is a nerve above the ilioenguinal which is not visible here which is just under the 12th rib and that is known as the subcostal nerve. So therefore the subcostal nerve, the iliohypogastric and the ilioenguinal these nerves are the ones which are likely to be injured when we are doing a posterior nephrectomy through the posterior approach and therefore these nerves have to be safeguarded. These are all the branches of the lumbosacral plexus. Thank you very much for watching. Dr. Sanjay Sanyal signing out. If you have any questions or comments please put them in the comment section below. Please like and subscribe.