 This section, my name is Dr. Sanjay Sanyal and the camera persons as usual, Jenny Glover, Sahiya and Zalika Stewart. So this section is on the posterior aspect, that is the gluteal region and the back of the thigh. Trust me, it is easier said than done. There were at least two kilos of fat, it took me one full day to remove it. Okay, so what do we see in front of us? Straight away we can see this big, huge muscle in front of us. This is the gluteus maximus and as I told you in class, the gluteus maximus fibres, they take attachment from the outer surface of the iliac bone behind the posterior iliac line and of course there are many other attachments and all the fibres, they come infrolaterally, they converge and the fibres, three fourths of the fibres, they get attached to the iliotibial tract and you can see the iliotibial tract and the fibres getting inserted onto the iliotibial tract. Incidentally, since we are on this topic because I want to be mentioning it again, further anteriorly you can see that there is another muscle which is also attached to the iliotibial tract and that is the tensile facial ladder but we are not going to talk about it. What I wanted to show you was the iliotibial tract which goes all the way down and gets inserted onto the fib, the tibia, all the way down, okay. Now what we will do, we will pick up the gluteus maximus, I have already incised it here near its attachment and I am going to gently reflect it. It is a very strong and a very big muscle as you can see here, it has got multiple bundles of fibres, it is a posterior muscle, it is a red muscle, okay. And once I reflect it, you will see deep inside that the deep one fourth of the fibres they get attached to the gluteal tuberosity which is just on the upper part of the posterior aspect of the femur. This is the prone cadaver and this is the left side, so this is about the gluteus. What else can we see? We can see the gluteal nerve, the inferior gluteal nerve coming and it is supplying the gluteal, gluteus maximus and this is a cut end of the inferior gluteal artery and this is the other cut end of the inferior gluteal artery but I will show you all of it when I come to the other structure. So this is the inferior gluteal nerve. Now that I have reflected the gluteus maximus, what do we see here? We see this muscle, this muscle, this also have cut but actually it was attached here. This is your gestate, this is the piriformis. This is the piriformis muscle and what other muscle can we see? We can see this muscle here, this also have cut here which is getting inserted onto the greater trochanter of the femur, this is the greater trochanter. This is the gluteus medius and I told you in class the fibres, the gluteus medius they get attached from between the posterior and the anterior gluteal line and they go vertically down and get inserted onto the greater trochanter. Now before I proceed any further, let me just reflect, I have cut the piriformis and the gluteus medius near the attachment to the greater trochanter. The piriformis gets attached to the tip of the greater trochanter. So I have cut it here, let me quickly reflect to show you the gluteus minimus and this muscle that you see here, deep inside this is the gluteus minimus. Okay, we will not talk about the gluteus medius minimus anymore, I just reflected it to show you the gluteus minimus. Let us come back to what are the other things that we can see. So I am going to put back the muscle in its normal place as it was before I removed it. Just to bring you up to speed, this is the piriformis which was getting attached to the tip of the greater trochanter and these are the fibres of the gluteus medius. As you know the piriformis takes origin from inside the pelvis, from the sacrum and it comes out through the greater sciatic foremen and as it comes out it divides the greater sciatic foremen into a suprapiriformis compartment and an infrapiriformis compartment and that is what we see here. We see some important structures coming out from the, let us remove the gluteus, the inferior gluteal vessels out of the way and we can see the three most important nerves coming out from the infrapiriformis compartment. Can we see this big nerve here? This is the sciatic nerve. Then we have this nerve here, this is the inferior gluteal nerve and you can see it is coming and supplying the gluteus maximus. If you have gluteal nerve S1, S2 posterior rami. And I give you a mnemonic. I said that going from lateral to medial we have SGP. Can you see this P here? This is the pudendal nerve. I have not told you about the pudendal nerve because pudendal nerve supplies the perinium. It comes out and it will go into the pelvis again, into the perinium to be more precise. So this is the greater trochanter, this is the ischial tuberosity. This is the greater trochanter. So these vessels, especially the sciatic nerve, it runs between the greater trochanter and the ischial tuberosity and this is where it rubs against the ischial tuberosity to produce what is known as sciatica. Incidentally, I have told you also that when it is emerging from under the pyriformis, it can get trapped under the pyriformis to produce what is known as pyriformis syndrome. Okay. So let's continue. Let me just reflect the sciatic nerve and let me just remove these muscles to show you which are the other deep gluteal muscles. One of them is the pyriformis, as I've already told you in the class. If you remember going from above downwards, we had three other muscles. Can you see this tendon in the middle here? This white structure. This is the obturator internus tendon and the obturator internus muscle, as I told you, also rises from inside the pelvis. The fibers make a sharp angle bend and this is the place where they're making a bend. Why are they making a bend? Because this is where the ischial spine is located and just under this will be located the obturator internus bursa. And it makes a bend here and it comes down and it goes inside and gets attached to the trochanteric fossa. Therefore, you see it disappearing here. And did we mention that there's a small sip of muscle above the pyriformis tendon and a small sip of muscle below the pyriformis tendon? So this is the superior gemulus and this is the inferior gemulus. They also arise from the, the superior gemulus arises from the ischial spine which is here and the inferior gemulus arises from the ischial tuberosity which is here. And both of them get inserted onto the obturator internus tendon. And these three together constitute what is known as the triceps coxsail. And we already mentioned that the nerve to obturator internus supplies the superior gemulus and the nerve to the next muscle which I'm going to show you now. Can you see this quadrangular shaped muscle here? This quadrangular shaped muscle, it is taking origin from the ischial tuberosity on one side here and it is getting inserted onto the quadrate tubercle of the femur. This is the quadratus femoris. So the nerve to the obturator internus supplies the obturator internus and the superior gemulus and the nerve to the quadratus femoris all of them are S1, S2, L5, S1. They supply the quadratus femoris and the inferior gemulus. And we can see very clearly here the sciatic nerve because the course of the sciatic nerve is very important. It is running from under the piriformis. It is running on top of these muscles between the, on top of the superior gemulus obturator internus, inferior gemulus and the quadratus femoris between the ischial tuberosity and the greater trochanter. By the way, this tendon that you see here is the sacro tuberous ligament, which is a very strong ligament arising from the sacrum to the ischial tuberosity. Part of it has been cut here. This is the sacro tuberous ligament. And this is of course the ischial rectal fossa, which we shall not talk about any further. So this is, these are the structures which I wanted to show you in the gluteal region. And since we are on the back of the thigh, I might show you some of the muscles, though I'm not completely dissected yet, but we are going to talk about it. And I'll show it to you right now itself. Let's start off from where we left off. This was the ischial tuberosity. And I told you in the class today that the muscles of the back of the thigh, they are all called the hamstring muscles, remember? And the main function of the hamstring muscle was extension of the hip, that is the thigh. So they all take origin. Most of them take origin from the ischial tuberosity and you can see that. You can see the hamstrings taking origin from the ischial tuberosity. And you will learn in class. So I'm going to quickly mention it. They are divided into two broad groups, a lateral group and a medial group. Because this patient is prone here. This is the lateral side of the patient. This lateral group is the biceps femoris. The bicep femoris has got a long head, which is taking attachment from the ischial tuberosity and a short head, which you can see. It is taking attachment from the surface of the posterior surface of the femur. That is the biceps. So this is the long head and these are the fibers of the short head. And both of them unite to form the bicep femoris. And I'll tell you the insertion later on. That is not part of this present discussion here. This is the bicep femoris. So this is the lateral group of the hamstring. What about the medial group of the hamstring? Again, we have two muscles. And both of them are taking attachment from the ischial tuberosity. This muscle that you see here on the top, the tendon was so friable that while I was dissecting it, it got partially torn. This muscle that you see, you can see the tendon, the muscle is tendinous, more tendinous. This is called the semi-tendinous muscle. And partially under the semi-tendinous muscle is this muscle here. This is also a part of the hamstring and this is called the semi-membranosus. So these are the other two muscles on the lateral group of the hamstrings. To complete the story, we, if we go further down, we will see the hamstring component of the adductor magnus, which I shall tell you later in class. And remember in the class, I was telling you something called the pestanseriness, which is a tripartite insertion of three tendons on the medial side of the tibia. One of them was the sartorius. The second attachment is a muscle called gracilis, which you can't see here because it's in the medial compartment. And the third muscle of that pestanseriness is the sartorius gracilis and semi-tendinousus. This also gets attached to the pestanseriness. And before I conclude, let's trace the shitegnerve. Can you see the shitegnerve coming down? It is running between these two landmarks. It continues on the back of the thigh. It is running on the back of the thigh. You can see it is running behind the hamstring muscles. And we can see it between these two groups of hamstring muscles. And we can see that somewhere, usually at the junction between the upper two-thirds and the lower one-third of the thigh, it divides into a lateral nerve and a medial nerve. And you can see the lateral one is called the common fibular and the medial one is called the tibial. The rest of the course of the shitegnerve, I will show it to you when I come to the popliteal fossa, which is located here. But right now, these are the muscles I wanted to show you. So we have discussed the muscles of the gluteal region. And we mentioned the muscles of the hamstring compartment, namely the hamstring muscles, and I have shown you the course of the shitegnerve. Thank you very much for watching, ladies and gentlemen. Have a nice day. Thank you, camera persons. If you have any questions or comments, put them in the comment section below. Dr. Sanjay Sanyal, signing out.