Pelvic Walls – Pelvic Floor

by James Pickering, PhD

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    00:00 If we now move on to the actual walls of the pelvis then we have a lateral wall, a posterior wall and then anterior wall, but actually, look at the orientation. If you look at the orientation of the pelvis, you can see that it’s kind of running down in this direction.

    00:17 A lot of the weight which is coming down here is actually being borne on the pubic symphysis.

    00:22 It’s not tilted square. It is actually tilted quite inferiorly. So, the actual pelvis is tilted. So, we have this passageway coming down through here, allowing the... allowing the baby when it’s being borne to pass through the pelvis and it takes this kind of this direction.

    00:44 If we look at the anterior wall of the pelvis, we can see it’s made up of the pubic symphysis and the various pubic rami, superior and inferior pubic rami, because this is the anterior wall.

    00:57 The lateral wall over here, we can see is made up of some important muscles and membrane.

    01:04 Importantly, we have this muscle... this muscle, here, we can see is running all the way over here. This is obturator internus muscle, obturator internus. It lines the lateral wall of the pelvis and is within the obturator foramen. It is really important, you remember, that the obturator muscle, obturator internus muscle is on the lateral wall of the pelvis. Its tendon passes out through here. Its tendon actually goes to, in a way, goes to attach on to the femur and it passes out to the pelvis via the lesser sciatic foramen. So, remember that the tendon of the obturator internus actually leaves the pelvis. What we can see lying on top of obturator internus muscle is this thin sheet and this is obturator fascia.

    02:03 So, we have the obturator foramen, filling the obturator foramen is obturator internus and then you have obturator fascia and again, that’s important, we will come back to it.

    02:15 This forms the lateral wall of the pelvis. We can also see we have got this defect here and that allows obturator artery, nerve and vein to leave the pelvis and pass into the medial compartment of the thigh. If we then look posteriorly, we find we have the sacrum most posteriorly and we have some muscles radiating from the sacrum from the coccyx down here that form this posterior boundary. Posterolaterally, we can see we have got coccygeus muscle, you can see that muscle here. And then superior to the coccygeus, we find we have piriformis. And piriformis is running out of the pelvis. And this also goes to attach to the femur. It attaches the greater trochanter of the femur, it’s a lateral rotator of the thigh. But, it originates from the anterior surface of the sacrum and it passes out through the greater sciatic foramen. Remember that passing out of the greater sciatic foramen superior to it was the superior gluteal blood vessel and passing out to the pelvis inferior to it was the inferior gluteal artery and also the internal pudendal artery.

    03:29 What we have here, inferior to the piriformis, is coccygeus. Coccygeus is running from the coccyx to the ischial spine. It runs on the inside of the sacrospinous ligament. So, when we look posteriorly at the ligaments of the pelvis, we can see the sacrospinous ligaments.

    03:51 But, lying on the inside of the sacrospinous ligament, we find we have coccyx... coccygeus muscle... we find we have the coccygeus muscle here. Here, I have mentioned both piriformis and obturator internus exit the pelvis via the greater and lesser sciatic foramina, respectively and that the obturator membrane has a thickening that runs from the superior pubic ramus to the ischial spine and this, as we move on to the pelvic floor, is really important.

    04:25 If we have running along here, we see we have this thickening. This is an important thickening of the obturator fascia, obturator membrane that's lying like medial to obturator internus muscle. This thickening runs from the superior pubic ramus up here all the way to the ischial spine. And it forms an important attachment site for the pelvic floor muscles, which we are now going to talk about.

    About the Lecture

    The lecture Pelvic Walls – Pelvic Floor by James Pickering, PhD is from the course Pelvis.

    Included Quiz Questions

    1. Greater sciatic
    2. Lesser sciatic
    3. Obturator
    4. Sacral
    1. Tendon of obturator internus
    2. Inferior gluteal nerve
    3. Sciatic nerve
    4. Inferior gluteal vessels
    5. Nerve to quadratus femoris
    1. Superior gluteal nerve
    2. Coccygeus
    3. Sciatic nerve
    4. Pudendal nerve
    5. Nerve to obturator internus

    Author of lecture Pelvic Walls – Pelvic Floor

     James Pickering, PhD

    James Pickering, PhD

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    Very clear and helpful
    By Jenny M. on 24. February 2020 for Pelvic Walls – Pelvic Floor

    Very clear and helpful. Love this anatomy course. thank you.

    By William S. on 05. December 2019 for Pelvic Walls – Pelvic Floor

    Lecture is very easy to follow. Overall, it is very helpful

    Very helpful thankyou!!
    By Sophie W. on 13. October 2018 for Pelvic Walls – Pelvic Floor

    I actually disagree with the above. Definitely really easy to follow, especially with the colour changes on the diagrams. It is, after all, an anatomy lecture and he teaches in a way that does allow you to think contextually for yourself without being super explicit about it. Thanks James

    not helpful
    By syed s. on 15. August 2018 for Pelvic Walls – Pelvic Floor

    he is stating sabotta diagram and not explaining in conceptual way