 Good day everybody, this is Dr. Sanjay Sanyal, professor of department chair. This is going to be a demonstration of the hemipelvis. I am holding up the left side hemipelvis in front of you. Now before I begin I need to tell you that the pelvis is an extremely complex structure and it can be viewed from many different perspectives. So this is going to be a demonstration of the overall hemipelvis with a few salient points and the gluteal region and the sacroiliac joint. So before I start, the pelvis is composed of three bones which are fused together and if you were to take a look inside the acetabulum, you will see a fade triangular line. That was the location of what is known as the triradiate cartilage. This is an x-ray of the pelvis of the child to show the triradiate cartilage and the alia of the hemipelvis are completely separate. The triradiate cartilage fused in the age of about 20-25 years and it formed one complex bone. Therefore if you were to use the triradiate cartilage as a reference point the portion which is posterior superior is the alia. The portion which is anterior is the pubic bone and the portion which is inferior is the ischium. So therefore the pelvis is composed of ilium, pubis and ischium. Having mentioned that, now let's take a look at the parts. This which I'm tracing right now, this is the superior pubic ravers and we can see that there's a line here. This is the ilio-pectinial line and there's a elevation here. This is called the iliopubic eminence which gives attachment to theectinial arch which comes from the savas minor. If you were to trace the superior pubic ravers you find that it goes to projection here. This is the pubic tubercle. And the remaining portion of that is called the pubic crest. And then we have the body of the pubis and then we have the inferior ravers of the pubis and somewhere here it fuses with the ischial ravers and forms the ischium pubic ravers and this fusion is called synostosis. This occurs approximately the age of nine years. Then we see this opening here. This is the obturator for eminence. In life this is covered by a membrane called the obturator membrane and attached to the inner surface of the membrane we have the obturator internus muscle and attached to the outer surface we have the obturator externus muscle. Then we have this, this is the ischial tuberosity and if you were to look very closely you find that it is also formed from a separate ischial epiphysis. Below the age of 16 years this ischial epiphysis can undergo aversion fracture and because most of the structures which are attached to the ischial tuberosity are muscles of the hamstring. So that is in effect rupture of the hamstring tendon that happens in hurdle jumpers or extreme sports. This is an x-ray of an adolescent to show aversion fracture of the ischial tuberosity. To continue up, now I have turned it and now I'm showing you the acetabulum. This is the acetabulum margin and this is the acetabular notch. So here the acetabulum margin is deficient and in life this is bridged over by a ligament called the transverse acetabular ligament. This depression that you see here this is filled with fat in life and this is called the acetabular fossa and this portion that you see here this is called the annular portion of the acetabulum which is actually governed by high land cartilage in life and this is the portion which articulates with the head of the femur to form the true hip joint. And in the depths of the acetabular fossa is attached a ligament called the ligament of the head of femur. Other end of it is attached to the head of the femur itself attached to the acetabular margin will be an acetabular labrum which helps to deepen the acetabular fossa. Now I'm going to turn and we can see that this is the iliac crest. Iliac crest has been divided into a medial lip an intermediate lip and a lateral lip. Each of these lips give attachment to the three fat muscles of the abdomen. Laterally we see this projection here this is the tubercle of the iliac crest and this forms an important landmark when we are in the abdomen. We see this projection in the front one above and one below. This is called the anterior superior iliac spine. This is the one which gives attachment to the inguinal ligament and also gives attachment to the muscle the sartorius. This is the anterior inferior iliac spine. This gives attachment to part of a muscle called the rectus femoris and the part is attached just above the acetabular. Similarly posteriorly we have two such projections. This is the posterior superior iliac spine this is the posterior inferior iliac spine. This is a clinical picture to show the location of the posterior superior iliac spine marked by two dimples and arrows. Now I will focus your attention to the lateral aspect of the ilium. This is the aila of the ilium. Aila means to be. And if you look closely you'll find three lines one line here, one line here and one line here. These are respectively referred to as the posterior gluteal line, anterior gluteal line and inferior gluteal line. The posterior gluteal line gives attachment to the gluteus maximus. Between the posterior and the anterior gluteal line we have attached the gluteus medius. And between the anterior gluteal line and the inferior gluteal line is attached the gluteus minimus. So therefore this whole surface is rather featureless because most of it is occupied by the attachments of the glutei muscles. Now let me come down to this structure here. We see this projection here. This is the ischial spine. And in life this gives attachment to a very important ligament called the sacro spinous ligament which I shall demonstrate to you when I put the sacrum together. So if you were to look above that we see this notch here. This is called the greater sciatic notch. And below the ischial spine we see another shallow notch. This is the lesser sciatic notch. In life again attached to the ischial tuberosity and to the sacrum is another strong ligament which goes up like that. That's called the sacro tuberous ligament. So when we put the two ligaments in place the sacro tuberous ligament and the sacrus spinous ligament we convert the greater sciatic notch into a greater sciatic foremen and the lesser sciatic notch into a lesser sciatic foremen. Now that's a very important landmark to be remembered because a very important muscle the pyriformis goes through the greater sciatic foremen and comes out. They devise the greater sciatic foremen into a suprapyriformis compartment and intrapyriformis compartment. And the lesser sciatic foremen gives passage to the pudendal vessels which enter into the perineum and operate internal standard. If you were to take a look at the inner surface there are again divided into two parts. An anterior portion which is shaped like a year and that is called the auricular part. And the posterior portion is referred to as the iliac tuberosity. The auricular part articulates with exactly the same part of the sacrum the auricular part of the sacrum and forms a synovial joint the sacro iliac joint. And the tuberosity the posterior part is the rough part which articulates with another structure in the sacrum which is also got the same name the sacro tuberosity and that forms also sacro iliac joint but this is a sacro iliac syncynismosis. And that is the one which transmits the weight of the vertebral column through the pelvis to the lower limbs. So therefore the sacro iliac joint is partly synovial and partly syncynismosis and that is what we see here. Now I'm going to put the sacrum. So this is the sacrum which I'm holding and I'm going to articulate it and here I have articulated it and I'm going to turn it around. So we see that the sacro iliac joint the anterior portion is the one which I mentioned forms the synovial part of the sacro iliac joint and the posterior portion is seen here is the one which forms the tuberosity of the sacro iliac joint. The tuberosity forms the syncynismosis and that's the one which transmits the weight of the vertebral column to the sacrum from the sacrum to the ilium and from the ilium to the femur. Therefore this is a complex sacro iliac joint and now that I have put the sacrum in place is I'm holding them with both my hands you can visualize that if there's a sacrosminous ligament extending from the ischial spine to the sacrum and a sacro tuberous ligament extending almost vertically down from the sacrum to the ischial tuberosity we convert greater sciatic notch into a foremen and the lesser sciatic notch into a foremen. So this is what we see when we put the sacrum in place. So that's all for now for that I'm being. Thank you very much for watching. If you have any questions or comments please put them in the comments section below. Please like and subscribe. Dr. Sanjay Sanyal signing out. Have a nice day.