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Pelvic Floor – Pelvic Wall and Floor

by Craig Canby, PhD
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    00:00 where the obturator membrane would be located. The pelvic floor is the inferior aspect of the pelvis. The pelvic floor is very, very important in supporting the pelvic viscera.

    00:12 If pelvic floor components become weak, you can have a prolapse of pelvic viscera. So, they would start to protrude inferiorly through a weak floor.

    00:24 The various components that form the floor would be the levator ani muscle, the coccygeus muscle, sometimes referred to as the ischiococcygeus. We have the perineal membrane and we have muscles that occupy the deep perineal pouch. We do see the levator ani in this view and we also see the coccygeus muscle in this view, but the perineal membrane and the deep perineal pouch will lie just inferior to the muscles that are forming the pelvic floor. So, we'll have an opportunity to view them in greater detail.

    01:15 As we can see in this slide, the pelvic floor does provide for openings. This will allow the passage of various components that are found within pelvic region. Here, we have an anterior opening, or hiatus. This is the urogenital hiatus. And so, urogenital structures can pass through this particular opening in the floor. And just posterior to it, we have a narrower opening or hiatus and this is the anal hiatus. And so, the anal canal will pass through this smaller opening. Now, we'll focus our attention on the other components of the pelvic floor, the perineal membrane and the deep perineal pouch. There are gender differences between men and women of this particular region. We'll explore those differences a little bit. But, here, we're looking at the perineal membrane, a deep perineal pouch in a man. The first component to point out has been reflected almost in its entirety, but here, we have a membranous structure that's being pulled back just a little bit by the forceps. This represents the perineal membrane. It is covering everything that we see in through here. So, it has been removed to kind of open up our view to see some of the other contents, then, that are located deep to it and those contents that are deep to the perineal membrane are located in the deep perineal pouch. So, those contents would be the urethra and we see the lumen of the urethra here.

    03:03 So, it's passing through that urogenital hiatus that we saw in the pelvic floor.

    03:09 There is muscle surrounding it at this level and those muscle fibers constitute the external urethral sphincter. We also see muscle fibers that are running transversely through the deep perineal pouch. These muscle fibers constitute the deep transverse perineal muscles and they meet in the midline. So, we do have a right one and a left one.

    03:38 Embedded within the deep perineal pouch in a man would be the bulbourethral glands, also referred to as Cowper's glands and one of those has been exposed here. And so, the muscle has been removed, lifting off the roof, so that we can see the bulbourethral gland here in the deep perineal pouch. Here are the muscles still intact. And you can kind of see the bulge of that bulbourethral gland. Lastly, you'll have neurovascular structures that supply the penis. They're coming into this area right through here. These neurovascular structures pass through the deep perineal pouch and then we can see them emerging at this particular point and then they will follow the penis.

    04:31 Here, we're looking at perineal membrane and deep perineal pouch in a woman. The membrane, unlike the previous slide, is intact. So, here is this whitish perineal membrane fully covering the deep perineal pouch. Structures that are found in the deep perineal pouch in a woman would include the urethra and we see that right in through here. We can also see the external urethral sphincter. So, these are certainly shared between men and women. If we peel back the perineal membrane, we would see the same deep transverse perineal muscles meeting in the midline. But, two structures that are unique in women, which are not depicted here because the membrane is intact, in place and is covering them up, but two structures unique to the deep perineal pouch in a woman would be the compressor urethrae muscle and the sphincter urethrovaginalis muscle. There is sexual dimorphism of the pelvis or


    About the Lecture

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


    Included Quiz Questions

    1. Levator ani muscle
    2. Piriformis muscle
    3. Obturator internus muscle
    4. Obturator externus
    1. Compressor urethrae muscle
    2. Deep transverse perineal muscle
    3. Sphincter urethrovaginalis muscle
    4. Internal urethral sphincter muscle
    1. Deep perineal pouch in men.
    2. Deep perineal pouch in women.
    3. Deep perineal pouches of both men and women.
    4. Along the periphery of the perineal membrane.
    5. Is unrelated to pelvic structures.

    Author of lecture Pelvic Floor – Pelvic Wall and Floor

     Craig Canby, PhD

    Craig Canby, PhD


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