Superior View – Pelvic Floor

by James Pickering, PhD

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    00:00 Let's have a look at their position in more detail. This is a view we are looking down on to the pelvic floor. All the organs have been removed and what we can see is anteriorly here, we have the pubic symphysis and posteriorly here, we have got the sacrum. We can see that running out to the greater sciatic foramen we have here, we can put in piriformis muscle.

    00:23 So, here would have piriformis muscle passing out in this direction. And then what we can see is that muscle we have seen a few times before running from the coccyx to the ischial spine, we have coccygeus, we can see that muscle here. Running from the coccyx towards ischial spine, we can see coccygeus, sometimes called ischiococcygeus. What we can see is here the midline, this is the midline we have here and we can see laterally, we have obturator internus muscle... obturator internus muscle. Here, we have the obturator canal for obturator artery, nerve and vein passing forwards, passing in this direction. On the medial surface of obturator internus muscle, we have that thick membrane. We have obturator membrane. We see this white kind of membrane here. And then we have that thickening and this thickening, the tendinous arch of obturator internus, half on the left side, half on the right side, is the origin of these levator ani muscles... origin of these levator ani muscles. And what we have is coming more anteriorly, coming down in this direction and running around the rectum is this one layer of levator ani and this is puborectalis muscle. So, this muscle that is running around the opening for the anus, which is here, the anus would be passing down through here. Running around and behind the anus is puborectalis.

    02:09 Then we have working more posteriorly this muscle, here. This is pubococcygeus and then running posteriorly again, we have iliococcygeus. And these three muscles, puborectalis, pubococcygeus, and iliococcygeus form levator ani. If we add coccygeus to levator ani, we have the pelvic floor.

    02:40 So, let's just do that once more. What we can see is that we have the midline here.

    02:49 We have apertures in the midline known as the urogenital hiatus, the anal hiatus here.

    02:57 These allow in the female, urogenital hiatus, the urethra and the vagina to pass through.

    03:02 In the male, we just have the urethra passing through. And then posterior to that, we have the anal hiatus in the male and female allows the anal canal to pass through midline.

    03:21 We can then see we have got the sacrum here, posteriorly. We can then see anteriorly, we have got the pubic symphysis. We have got the superior pubic rami here and here.

    03:31 We can see we have got obturator internus, obturator membrane and a thickening the tendinous arch of obturator internus... the tendinous arch of obturator internus. Remember, this is going to have the levator ani muscles running down from it. So, the first one, most anteriorly, that runs around the rectum, around the anal hiatus here, puborectalis. Then posterior to that, we have pubococcygeus... pubococcygeus and then posterior to that, we have iliococcygeus, which we can see here, iliococcygeus. Most posteriorly, but not part of levator ani running on the inside of the sacrospinous ligament, we have coccygeus or ischiococcygeus muscle here. And these four muscles form the pelvic floor. Levator ani being puborectalis, pubococcygeus and iliococcygeus, levator ani adding on coccygeus for the pelvic floor. They insert in the midline where we have a couple of important thickenings. We have the perineal body. The perineal body is positioned between the urogenital hiatus and the anal hiatus here and then running from the anus to the coccyx, we have the anococcygeal ligament. These muscles also blend with the walls of the prostate, vagina, rectum and the coccyx. So, previously, when I said laterally to the vagina you find the pelvic floor, hopefully, now, you can appreciate that laterally, we have the pelvic floor as it passes through the urogenital hiatus.

    05:25 What's the function... What's the function of these pelvic floor muscles? While they are important because they help to support and maintain the position of the abdominopelvic reservoir. So, they help to hold these in place. There are muscular floor so contraction of them will help to stabilize the organs in the pelvis. If they become weak then you are likely to have prolapse. They also help to withstand increases in intra-abdominal pressure. So, when you cough or when you sneeze, they can prevent these organs passing out through the pelvic outlet. They can contract and they can hold the pelvic organs in place.

    06:05 So, the function of these pelvic floor muscles is really important and remember, we have levator ani and we have coccygeus.

    About the Lecture

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

    Included Quiz Questions

    1. Ischial tuberosity
    2. Ischial spine
    3. Pubis
    4. Tendinous arch of the obturator internus fascia
    1. Coccygeus
    2. Puborectalis
    3. Pubococcygeus
    4. Iliococcygeus
    1. Obturator membrane
    2. Obturator artery
    3. Obturator vein
    4. Obturator nerve
    5. Pubic symphysis
    1. Puborectalis
    2. Pubococcygeus
    3. Coccygeus
    4. Iliococcygeus
    5. Obturator internus

    Author of lecture Superior View – Pelvic Floor

     James Pickering, PhD

    James Pickering, PhD

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