 Good day everybody. Dr. Sanjeev Sanyal, Professor of Department Chair. This is going to be a demonstration of the posterior aspect of the thigh. This is a broken ever. We should focus on the neurovascular structures that we can see in the posterior aspect of the thigh and in the process we should also describe what are the structures they supply. Let's start off with this one that we can see here. This is the shantygnur and we can clearly see it is arising from the gluteal region. So it comes to the thigh after it has crossed this muscle here. This is the quadratus femoris muscle and after that from here to here is the portion behind the thigh. After that it comes into the popetal fossa and then it goes to the leg. So let's take a look at the course of the shantygnur. In the gluteal region it is running on this bed which is composed of four muscles. Just to mention quickly, this is the superior gemulus. This is the operator internus. This is the inferior gemulus and this is the quadratus femoris. And in this position it can be injured if there is a posterior dislocation of the hip. But now we shall focus on after the quadratus femoris. Here we are seeing that the shantygnur is running in a neurovascular plane. Composed anteriorly that is in front of the shantygnur by this muscle that we can see here. This is the rectormagnus. More specifically this is the rector component of the rectormagnus and we can see the fibers are going obliquely down. And these are the fibers which get inserted onto the linear aspera. And superficially the muscles that we can see here, this is the hamstring muscles. More specifically, laterally we have this muscle here. This is the biceps femoris. We can see it is taking origin from the ischial fibrosis. This is the long head of the biceps. And it is then uniting with the short head of the biceps which I have lifted up here. Which takes origin from the linear aspera. And the two heads are then united to form the biceps femoris. And medially we can see these group of muscles. This is the semi-tentenosis. Also taking origin from the ischial tuberosity. And medially we can see this muscle here. And we can see upper portion is membranous. And fleshy. This is the semi-membranosis. So semi-tentenosis and semi-membranosis, medially, and the biceps femoris, laterally, these are the superficial muscles which overlie the sciatic nerve. So therefore the sciatic nerve runs in this neurovascular plane. So these are the hamstring muscles. Now I shall lift up these muscles. And I can show you how the sciatic nerve supplies branches to each of these muscles. The sciatic nerve has got two components. It's got a tibial component which is the pre-axial and the fibular component which is the post-axial. General rule is that the tibial component supplies branches to the hamstring muscles. And we can see that here. We can see one branch coming out here. We can see the other branches here. Supplying this, the biceps femoris. Short head. The biceps femoris is supplied by the common fibular component of the sciatic nerve. So semi-tendinosis is supplied by the tibial component. And the semi-membranosis is also supplied by the tibial component. And we can see the branches. And while we're looking at this, I shall draw your attention to yet one more branch which is present on this surface. And this is this one here. And we can see it is coming from the sciatic nerve here. This supplies the hamstring component of the ductrum agnus. And the hamstring component of the ductrum agnus is visible here. If you were to look medially, we can see a tendon here. This is the adductor tendon. This comes from the hamstring component of the ductrum agnus and descends vertically down medial to the adductor hiatus and gets attached to the adductor tubercle. This is the hamstring component. And that is supplied by the tibial division of the sciatic nerve. So we can see all the branches of the sciatic nerve. Next we can also notice that somewhere on the posterior aspect of the thigh, the sciatic nerve is divided into two of its original components. One component is the lateral one. This is known as the common fibular component. And this is the medial one. This is referred to as the tibial component. And then they go down into the pubricial fossa. The common fibular component runs laterally under cover of the bicep femoris. The tibial component runs vertically down from one apex of the pubricial fossa down to the lower apex. The rest of the course of the sciatic nerve, in this case tibial nerve and the common fibular, we shall describe when we come to the leg. So that is one aspect of the neurovecular structure which I have demonstrated. The sciatic nerve can be injured if there is excessive friction against the ischial tuberosity and that is known as jogger's sciatica. The sciatic nerve is the most important, the largest nerve in the human body and it supplies all structures in the posterior aspect of the lower limb. And if this is injured then it can lead to paralysis right up to the sole of the foot. The next neurovecular structure I will draw your attention to are these blood vessels and I am going to lift them up one by one. Let us lift up this one here. This is one set of blood vessels we can see here. Next set is this one. The third set is this one. And the fourth set I am going to go between the two halves of the hamstrings and I will show you this blood vessel here. These are known as the perforating arteries. How do these perforating arteries arise? The perforating arteries come from the profunda femoris artery which is on the anterior spedulothi. The profunda femoris is the largest branch of the femoral artery and it runs very close to the insertion of the adductor magnus on the linear aspirin. And then as it descends down it gives four perforating arteries respectively numbered perforating one, two, three and the fourth. The last perforating artery is the termination of the profunda femoris. Let us take a quick look at the distribution of the perforating arteries. The first one we can see it is giving a branch up here. This is the first perforating artery which I had lifted up and this is giving this branch here. This first perforating artery, this branch, it participates in what is known as the cruciate anastomosis around the greater trochanter. The first perforating artery, a lateral circumflex femoral, a medial circumflex femoral and a branch from the inferior gluteal. This is the inferior gluteal vessels that we can see here. All these four anastomos around the greater trochanter and that is referred to as a cruciate anastomosis. This cruciate anastomosis plays an important role in providing a collateral circulation during iliofemoral occlusion. To continue with the rest of the perforating artery we can see that it comes up here and it gives a set of branches to the muscle overlying it, namely the bicep femoris. And after that we can see it is going between the bifurcation of the sciatic nerve and then it continues and we can see on the other side. Each of these perforating arteries, they divide into a descending branch and a descending branch, which is the basic. Of course, there will be other branches also. Anastomosis with the next perforating artery, which is this one here. This one also we can see we had to purposely cut it here in order to retract this muscle. This was the continuation and we can see it is penetrating through the bicep femoris and then it is coming out and it is anastomosing with the first perforating artery. The third one is this one, which is also going through the short end of the biceps and it is coming on this side. And finally as I mentioned, this is the fourth perforating and all of them are forming a continuous anastomotic arcade. This anastomotic arcade is located principally between the adductor magnus, the bicep femoris and the semimembranosus and semitendinosus. And in this fashion, they supply all the muscles and other structures in the posterior compartment of the thigh. We must remember that the posterior compartment of the thigh does not have any blood vessel of its own. So therefore, the blood supply to the posterior compartment of the thigh has to be provided by means of these perforating arteries, which come from the profundum femoris artery, which is the largest branch of the femoral artery. As I mentioned, this is the fourth perforating artery. The fourth perforating artery is the termination of the profundum femoris and this is usually, as we can see here, very close to the adductor hiatus, which is an opening through which the femoral vessels become perforatial vessels and this is the region of the adductor hiatus. So this is the fourth perforating. We can see yet another counterpart of the perforating coming from the perforatial vessel itself and that is this one here. This is quite often seen in many dissections and we can see that one here. And this also participates in supplying the hamstring muscles, more specifically the semi-membranous muscle, as we can see here. So this is the distribution of these perforating arteries and before I conclude, I will draw your attention to the medial side of the thigh and we can see these are the branches of the veins from the perforating. These, as they travel medially, they communicate with the superficial veins on the medial side of the thigh and these communicating veins, because they pierce through the deep fascia, that is the fascial end of the thigh, they are referred to as the perforating veins. Blood supply normally flows from superficial to deep. If there is incompetence of the valves in these perforating veins, blood can flow in the reverse direction, that is from deep to superficial and can lead to what is known as varicose veins. If it is in the thigh, it is referred to as saphena varix. So these are the neurovascular structures and the supply and the muscles of the posterior compartment that I wanted to show you. Thank you very much for watching Dr. Sajju Sanyan signing out. David, who is the camera person, if you have any questions or comments, please put them in the comment section below. Have a nice day.