Ischium – Osteology of Lower Limb

00:01 with as we look at the attachment sites later on of the gluteal muscles. Now let’s turn to the ischium. The ischium is most posteriorly located, and it’s the postero-inferior aspect of the hip bone, and also the acetabulum. So here on this lateral surface where we can see the acetabulum, if the ilium was superior from this line here, then the ischium is coming down into this region. So the ischium is everything below this line we can see here. Again, it’s uniting with the pubis and the ilium at the acetabulum. We can see the body of the ischium on this medial surface. So here, the organs of the pelvis have been removed and we can see a nice clear body of the ischium. Remember, this connects the ilium and the pubis at the acetabulum. We can see it’s on the acetabulus surface here. We can also recognize the ramus of the ischium, and the ramus of the ischium is important. It connects the inferior pubic ramus of the pubic bone. So here, if we look at this lateral view, we can see running down here from the body of the ischium, we have the ramus of the ischium, and that runs towards the inferior pubic ramus. Collectively, that forms the ischiopubic ramus here. We can see that on this lateral surface. We can also see it coming down here on this medial surface, and we can see it running down here on this superior surface. It’s also going to form the obturator foramen which we can see this large space here. If we look at the ischium in some bony landmarks, then some important bony landmarks protruding posteriorly from the ischium, we have two. We have the ischial spine and the ischial tuberosity. Seen here on the medial surface view, but projecting posteriorly, we have the ischial spine superiorly and the ischial tuberosity inferiorly. On this lateral view, we can also see it.

02:05 So again here is anteriorly, and projecting posteriorly, we have the ischial spine and we have the ischial tuberosity. These bony landmarks are important as they create the greater and lesser sciatic notches. We can see here, we have the greater sciatic notch running from the posterior inferior iliac spine all the way around to the ischial spine here, the greater sciatic notch running around here. We then have running from the ischial spine this little concavity here, and that is the lesser sciatic notch. Later on, we’ll see how these are converted into foramina. But now let’s turn to the pubis or the pubic bone. This is the