Ilium and Ischium – Pelvic Wall and Floor

by Craig Canby, PhD

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    00:01 Now, let's take a look at the ilium. This is a lateral view and because of the surface presentations or features that we see here, they are quite remarkable and pronounced. This would be more typical of a male.

    00:14 Here, we're looking at the ilium, in through here and some of the components of the ilium that you should be familiar with would include the iliac crest. That is seen as this curved structure along the superior aspect of the ilium. At this point along the iliac crest, we have a bony eminence that is referred to as the tubercle. We also have two bony eminences anteriorly located. So, the anterior termination of that iliac crest leads you to a bony prominence that is readily palpable in a human body. And this is the anterior superior iliac spine.

    01:04 We also have an anterior inferior iliac spine and we see that eminence at this location.

    01:13 On the posterior aspect, we also have two iliac spines. This is the posterior superior iliac spine and then this is the posterior inferior iliac spine.

    01:30 On the lateral aspect here, we see three prominent gluteal lines. This is the posterior gluteal line. This is the anterior gluteal line. And then along here, we have the inferior gluteal line. And these features will make greater sense when you study a unit on the gluteal region. Lastly, we have this prominent notch on the posterior aspect of the ilium. It is just inferior to the posterior inferior iliac spine and this major notch is referred to as the greater sciatic notch.

    02:18 Now, we're looking at the ilium and our view is a medial view. And there are three features to point out in this particular view. The first is this line that we see right in through here. This is called the arcuate line. And then above that is a winglike extension of the ilium. It is also visible on the lateral view where we had the gluteal lines. A winglike extension is known an ala. So, this is the ala of the ilium. And then located right along here, you see the articular surface of the ilium and this articular portion articulates with sacrum. Now, let's turn our attention to the ischium and our focus here will be a lateral view. The ischium is in this general area and it extends out anteriorly and inferiorly to about this particular point. Features of the ischium that you should be familiar with would include this bony eminence. This is at the inferior aspect of the greater sciatic notch and this bony eminence constitutes the ischial spine.

    03:52 Immediately below is a smaller notched-out area, so this is associated with the ischium.

    04:00 This is referred to as the lesser sciatic notch. Then we have this prominent bony projection.

    04:10 This is referred to as the ischial tuberosity. This supports our weight in a seated position.

    04:17 And then we have an anterior projection of the ischial tuberosity. This is the ischial ramus and it will join another ramus, that being, specifically, the inferior ramus of the pubic bone, which is shown here and this is the junction between those two rami.

    04:43 The last bone that makes up the pelvic bone is the pubic bone. Here, we're looking at a medial view. And let's highlight some of the features of this particular bone. The first feature is this ramus located along here. This is referred to as the superior pubic ramus. Along its superior border, we see a line. This is referred to as the pectineal line, also known as the pecten pubis. If we follow the pectineal line out medially, we will see that there is a bony eminence at this location and this is called the pubic tubercle. Along here, we have the other ramus of the pubic bone. This is the inferior pubic ramus and as mentioned with the ischium, the inferior pubic ramus joins the ischial ramus.

    05:50 There is some controversy as to what constitutes the actual body of the pubis, but it is quite common and frequent to say the point at where these two pubic rami join in the medial aspect to form this area here. This is commonly called the body of the pubis and then this medial aspect along here represents a point of articulation with the opposite body of the pubic bone.

    06:24 This, then, constitutes the symphyseal surface.

    About the Lecture

    The lecture Ilium and Ischium – Pelvic Wall and Floor by Craig Canby, PhD is from the course Abdominal Wall.

    Included Quiz Questions

    1. Anterior superior iliac spine
    2. Greater sciatic notch
    3. Anterior inferior iliac spine
    4. Posterior superior iliac spine
    5. Posterior inferior iliac spine
    1. 3 lines
    2. 4 lines
    3. 2 lines
    4. 1 line
    5. 5 lines
    1. On the ischium
    2. On the ala
    3. On the pubis
    4. On the ilium
    5. On the ischial tuberosity
    1. Ischial tuberosity
    2. Iliac crest
    3. Pubic ramus
    4. Ischial spines
    5. Pubic tubercles
    1. Ischium
    2. Ilium
    3. Pubis
    4. Symphysis
    5. Crest

    Author of lecture Ilium and Ischium – Pelvic Wall and Floor

     Craig Canby, PhD

    Craig Canby, PhD

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