 Good day everybody. Dr. Sajja Sanyal, professor of department chair. We are going to focus on the neurovascular structures and the relative supply on the gluteal region. This is the prone cadaver So this muscle that we have exposed here This is the gluteus maximus and you can see that it is arising in a very extensive way from the coccyx sacrum and from the outer surface of the alium posterior to the posterior gluteal line and the fibers are then converging here and this is The iliotibial tract that we can see here Where the three fourths of the superficial fibers get inserted and this aponeurotic expansion goes down and gets attached to the natural-atrial tubercle of GRD So what we are going to do now we have already cut the origin of the gluteus maximus and we are going to reflect it and We are going to go straight to the neurovascular structures and their supply When we reflect it we see the neurovascular structures. So let's take them one by one These neurovascular structures that we can see here. This is above the pyriformis. So this is the superior gluteal artery The superior gluteal artery is a branch from the posterior vision of the internal iliac and the superior gluteal artery supplies the structures Deep to the gluteus maximus namely the gluteus medius and gluteus minimus and tensor fissure letter When I reflect the gluteus medius Which I am doing right now We can see the rest of the neurovascular structures here, and I have lifted them up here and we can see that this is These are the other branches of the superior gluteal artery and These are the branches from this superior gluteal nerve the superior gluteal nerve root value is L5S1 and we can see the superior gluteal nerve is supplying the gluteus medius and We can see other branches Are supplying the gluteus minimus, which is here and we can see the gluteus minimus from the other side here and The superior gluteal nerve also supplies the tensor fissure letter, which is located further antrolaterally here So that brings me to the action of these muscles the gluteus medius and the gluteus minimus as you can see the fibers Are descending vertically down and they get inserted on the top of the greater trochanter both the gluteus medius and The gluteus minimus so therefore their main action is abduction of the hip and medial rotation They also have to stabilize the pelvis Especially when we are standing on one leg it prevents the other side pelvis from sagging down by virtue of their unique insert That brings me to a very important clinical correlation here If there's a deep penetrating injury in the gluteal region and the superior gluteal nerve is injured Then the gluteus medius gluteus minimus and the TFL will be paralyzed and that produces a condition known as Trending Berkside what happens in trend and Berkside When the patient is asked to stand on the leg of the paralyzed type The hip on the other side will sag down because the gluteus medius is not able to stabilize the pelvis That is called trend and Berkside and Because of that the person will develop one of three gates One is called the gluteal or the waddling gate or Outswinging gate or a high-stage gate So that is the manifestation of superior gluteal nerve injury from a deep penetrating stab injury Now let's take the next neuro vascular structure This is again the piriformis as I mentioned and we can see the piriformis is coming from the anterior aspect of the sacrum And my fingers is in the greater sciatic notch The piriformis emerges from the greater sciatic notch and by means of this narrow tendon It gets inserted onto the tip of the greater trochanter. So therefore the piriformis divides the greater sciatic foramen Into a suprapiriformis compartment, which I described just now which gives passage to the superior gluteal vessels and the superior gluteal nerve And it divides the Greater sciatic foramen into an infra piriformis compartment and that is this one here The portion below the piriformis is the infra piriformis compartment and what are the structures which are emerging through the infra piriformis compartment We can see this big nerve here I'm going from lateral to medial. This is the sciatic nerve. So this is the first structure The second structure which comes out is this one, which I have lifted up collectively This is the inferior gluteal nerve and the inferior gluteal artery and the vessels The inferior gluteal nerve is S1 S2 the posterior division and this the inferior gluteal artery Which is the branch from the anterior division of internal IAC This inferior gluteal nerve is the one which supplies The gluteus maximus and the artery also and we can see the cut portions of the nerve which were entering into the gluteus maximus This is one cut portion here. This is another cut portion the vessel Another cut portion and there are numerous cut portions. So we have to cut them here to reflect the gluteus maximus What happens when there is an injury of the inferior gluteal nerve? Inferior gluteal nerve injury will produce parallel to the gluteus maximus and action of the gluteus maximus is Extension and lateral rotation of the head. So therefore the patient will not be able to extend and lateral rotate the head Additionally more important action function of the gluteus maximus is To make the person sit from a standing position and stand from a sitting position or climb or walk uphill Just imagine when a person is standing and he is about to sit down on the chair His gluteus maximus is undergoing isotonic eccentric contraction, which is also referred to as controlled relaxation and Likewise from a sitting position when he's standing his gluteus maximus is undergoing Concentric isotonic contraction to enable him to stand So all these functions will be lost when inferior gluteal nerve is injured in this connection I can mention there is a condition called epicona syndrome Where there's a legion of the spinal cord just above the conus That means just above S3 and an epicona syndrome which can be due to a tumor The patient has very similar findings as gluteus maximus paralysis namely He has severe inability to extend and laterally rotate the hip So that is with respect to injury to the inferior gluteal nerve Next you can see here as I mentioned is the shiitake nerve So let's take a quick look at the formation of the shiitake nerve The shiitake nerve is formed inside the pelvis By a combination of the lumbar plexus and the sacral plexus the component from the lumbar plexus is L4 5 Which comes through the lumbosacral trunk and the sacral plexus S123. So that is the root value of the shiitake nerve In the pelvis it has got two components a pre-axial division and a post-axial division and here it is also met by What is known as the posterior femoral cutaneous nerve, which we cannot see very clearly here, but it unites with the shiitake nerve and as the shiitake nerve emerges from the infrabidiformis compartment The posterior femoral cutaneous nerve separates off and it supplies the skin of the back of the thigh and also the inferior gluteal region The rest of the shiitake nerve then descends down on this bed This bed is composed of the following four muscles. One muscle we can see here This is the superior gemalus The next muscle we can see here. This is the operator internus The next muscle that we see here is the inferior gemalus and the last muscle is the Quadratus femoris So this forms a bed for the shiitake nerve to pass through and it passes roughly midway between The greater trochanter and the ischial tuberosity and this is an important landmark if you want to keep shiitake nerve blocked We follow the portion midway between these two bony prominences Likewise when a person who is jogging for many years Friction of the shiitake nerve against the ischial tuberosity can produce shiitica This shiitica nerve can be compressed under the piriformis In about 12% of cases the one of the divisions of the shiitake nerve can go through the piriformis and in 0.5% of cases one of the divisions the common fibular division can come even above the piriformis These are the conditions when the piriformis is especially prone to compression or entrapment And this is referred to as the piriformis syndrome This typically occurs in skiers when they fall on their buttock and there is swelling and inflammation Which compresses the shiitake nerve and that can produce symptoms very similar to shiitica in terms of shooting pain on the back of the leg The shiitake nerve can also be enjoyed in posterior dislocation of the hip And after it has crossed these muscles the shiitake nerve then enters it to the thigh and We shall see the course of the shiitake nerve when we come to the thigh And we can see the shiitake nerve running on the back of the thigh till it reaches and shiitake nerve is the one which supplies everything on the back of the thigh, back of the knee, back of the foot, leg, right under the sole of the foot This is a photomicrograph of a distal stump of a ninja shiitake nerve showing axon regeneration That brings me to yet another neurovascular structure which I'm going to just show but I'm not going to mention the details And that is this here. I've lifted up a composite neurovascular structure here This is the pudendal nerve and the internal pudendal artery This complex it comes out from the greatest shiitake for a minute below the piriformis It winds around this pony prominence, which I can feel here and you can see a little bit here This is the ischial spine and then it goes back through this space This is the lesser shiitake for a minute and it enters into the ischial enulfosa And it runs in the canal called the pudendal canal or the alcox canal and supplies the structures in the perineum So therefore to summarize going from lateral to medial we have S, shiitake nerve, G, gluteal, inferior gluteal nerve and artery and P, pudendal, internal pudendal artery and pudendal nerve And just to complete the story, let me mention quickly the nerve supply of these deep muscles The piriformis is supplied by the nerve to piriformis, which is from the anterior ramai of S1, S2 The rest of the muscles, the superior gemalus and the operating ternus is supplied by the nerve to operating ternus, which is L5, S1 and the inferior gemalus and cortidus femoris is supplied by the nerve to cortidus femoris, which is also from L5, S1 the action of all these deep muscles is Lateral rotation of the hip. So if any of these nerves are injured, which is not very common Then there will be weakness of lateral rotation and that brings to the final point When do we use medial rotation and lateral rotation of the hip? On a day-to-day basis, when we are just walking with each step that we take our hip Rotates medially and the opposite hip rotates laterally and vice versa So therefore lateral and medial rotation of the hip is an unconscious thing Which we do not do consciously, but it automatically happens each time we walk So these are all the points which I want to mention about the neurovascular structures and the supply in the gluteal region Thank you very much for watching. Dr. Sanjay Sanyal signing out David O is the camera person. If you have any questions or comments, please put them in the comment section below. Have a nice day