Pelvic Wall – Pelvic Wall and Floor

by Craig Canby, PhD

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    00:00 When we think about the pelvis, the pelvis does present pelvic walls and those pelvic walls have various components. Here, we're looking at some osseous and ligamentous components on one of the walls.

    00:20 We'd have the same components on the opposite pelvic wall as well. But, the components of the pelvic wall would be bones, ligaments, apertures as well as muscles. And we're going to explore these various components in the subsequent slides.

    00:38 So, again, focusing on the pelvic wall, let's look at the bones and ligaments that help form the wall. And again, these are bilateral structures. So, we would have the coccyx and sacrum helping to form the wall. We also have the pelvic bones that would run inferior to the linea semilunaris, shown in through here. We have the sacrospinous ligament that is shown here running from the sacrum to the ischial spine and then we have a larger, more substantive ligament that's running from the sacrum to the ischial tuberosity. This, then, represents the sacrotuberous ligament. Apertures are formed within the pelvic wall and these apertures are openings that allow the passage of structures. One such opening is seen here. This is the obturator foramen. In life, most of this foramen is filled by an obturator membrane, connective tissue, and we'll have just a little bit of an opening here in this general region. Two other openings are seen here and these are fairly substantial in size. This is your greater sciatic foramen and this is your lesser sciatic foramen. These two foramina are formed by the sacrospinous and the sacrotuberous ligaments, which will convert the greater sciatic notch and the lesser sciatic notch into their respective foramina. So, your greater sciatic notch here is converted to the greater sciatic foramen by the sacrotuberous and the sacrospinous ligaments. Your lesser sciatic notch is converted into the lesser sciatic foramen, again, by the sacrotuberous ligament here and by the sacrospinous ligament above.

    02:53 There are many important structures that pass through these two foramina.

    02:56 When you look at the greater sciatic foramen, your have the Piriformis muscle Superior gluteal nerve and vessels, and the inferior gluteal nerve and vessels.

    03:06 The sciatic nerve, the posterior cutaneous nerve of thigh, the nerve to the quadratus femoris muscle, the nerve to obturator internus muscle, the pudendal nerve and the internal pudendal vessels.

    03:19 The structures that pass through the lasser sciatic foramen, are the nerve to the obturator internus muscle, the pudendal nerve, the internal pudendal vessels, and the tendon of obturator internus muscle.

    03:32 In addition to the bony and ligamentous structures, the pelvic wall is also partially formed by the presence of muscles. We have the obturator internus muscle and the piriformis muscle contributing to the wall in this particular slide.

    03:52 Your piriformis muscle is shown here. It is originating from the anterior pelvic surface of the sacrum and it'll exit the pelvis by passing out through the greater sciatic foramen and we see that occurring right in through here. The obturator internus is shown over here.

    04:17 We do not see it in its entirety because it's going to disappear on us. The whitish membrane that we see attached to it is the obturator fascia, but you see the reddish muscle fibers just deep to that fascial component, so, again, obturator internus. And then right in this area, you see the passageway through the obturator foramen, that opening that is left just above where the obturator membrane would be located.

    About the Lecture

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

    Included Quiz Questions

    1. Sacrotuberous ligament
    2. Sacrospinous ligament
    3. Obturator foramen
    4. Obturator internus
    5. Piriformis muscle
    1. 3
    2. 1
    3. 2
    4. 4
    5. 7

    Author of lecture Pelvic Wall – Pelvic Wall and Floor

     Craig Canby, PhD

    Craig Canby, PhD

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