Pelvic Floor

00:01 Now let's have a look at some structure of the pelvic floor, the components that really make up this muscular layer.

00:08 So here we see the pelvic floor.

00:10 And what we're going to add in now is this shelf.

00:13 This layer of muscle that is suspended across the pelvic cavity.

00:19 So these are the muscles of the pelvic floor, or the pelvic diaphragm. A bit like the thoracic diaphragm.

00:26 This is a thin layer of muscle that has the various organs we've spoken about before bladder, uterus, rectum sitting on top helping to hold them in position within the pelvis.

00:38 There'll be various apertures within this muscular layer that will see that allow the various tubes to pass through like the urethra, the rectum, the anal canal, and the anus.

00:49 So here we can see the pelvic cavity above the pelvic floor, and the perineum is now below the floor.

00:56 That was why previously when we looked at that blood vessel, that neurovascular bundle, the pudendal neurovascular bundle, it left the pelvis via the greater sciatic foramen.

01:07 And then as it came underneath through the lesser sciatic foramen, it found itself beneath the pelvic floor, within the perineum.

01:16 So let's have a look at some of these floor muscles.

01:19 We have obturator internus muscle. We mentioned before and piriformis.

01:22 These helping really to form the lateral aspects of that pelvic floor.

01:26 An important structure though is a tenderness arch.

01:30 This tenderness arch is running all the way along that lateral aspect of the pelvis.

01:36 And what this tenderness arch does is it serves to form muscle attachment sites for the muscles of the pelvic floor.

01:44 So here we can see the tenderness arch really coming from the ischial spine posteriorly and it arches towards the pubic bone anteriorly and that forms a tenderness arch.

01:55 It's a thickening of those muscle layers and that serves to form an attachment site for those muscles.

02:02 One of those muscles coming away from that tenderness arch and coming from the pubic bone is puborectalis.

02:09 Another muscle is pubococcygeus coming from the pubic bone all the way back to the coccyx.

02:15 And here we have the iliococcygeus muscle coming from the ileal aspects of the tenderness arch.

02:21 and again passing to the coccyx.

02:23 These three muscles puborectalis, pubococcygeus, and iliococcygeus combined to form levator ani.

02:32 And these are key muscles within the pelvic floor.

02:36 Another muscle associated with the pelvic floor is the coccygeus muscle.

02:40 And it's coccygeus and levator ani, which form your classic pelvic floor muscles.

02:46 Obturator internus and periformis don't really form muscles of the pelvic floor as their position to laterally.

02:53 Coccygeus and levator ani.

02:55 Levator ani it's three parts from the pelvic floor muscles.

03:00 Let's have a look at the pelvic floor superiorly.

03:02 This helps us to see how these muscles come from the tendinous arch laterally and then merge in the midline.

03:09 So we'll zoom in and we'll remove one of these because it'll help us build up the picture.

03:14 So the complete muscle pelvic floor is they're located on the right hand side of the pelvis or the left side of the screen.

03:22 The pubic symphysis anteriorly is at the bottom of the screen, remember.

03:25 So we're looking down into the pelvis.

03:28 The first muscle we can put it in his coccygeus.

03:30 We can see coccygeus coming from the tendinous arch anteriorly passing back to the coccyx.

03:36 So when you see it coming from the ischial spine, and then passing back to the sacrum and coccyx.

03:41 This is coccygeus.

03:44 We have another muscle called iliococcygeus.

03:46 This is coming from the tendinous arch and passes back to the coccyx.

03:51 It becomes quite ligamentous towards that attachment site at the coccyx.

03:56 And sometimes it's known as the ligament of raphe becomes quite ligamentous like I say as it blends with that bony structure of the coccyx.

04:04 We then have puborectalis.

04:06 This muscle is coming from the pubic bone and it passes all the way posteriorly to join with the muscle fibers of the corresponding contralateral muscle.

04:16 This form is a sling that is going around the rectum and that helps to cause that rectal angle.

04:23 So puborectalis really is running posterior.

04:26 It loops around the rectum and then unites with the same muscle from the opposite side.

04:33 What the muscle of levator ani.

04:35 We haven't mentioned before is pubococcygeus.

04:38 Pubococcygeus is extending from the pubic bone and it's passing all the way posteriorly to attach to the coccyx and the sacrum.

04:46 You then add all of those muscles together.

04:49 And you can see we've got puborectalis, pubococcygeus, iliococcygeus, and the coccygeus muscle forming the pelvic floor.

04:58 These muscles combine in the midline as well as you can see, and they help to form the floor of the pelvic cavity.

05:06 What you can notice there's a few openings or hiati within the pelvic floor muscle.

05:11 Here we're going to see the anal hiatus and hearing see the urogenital hiatus.

05:17 Passing through the anal hiatus is going to be the anus as it transitions from the rectum, anal canal, into the anus as it enters into the perineum.

05:25 And here we can see the urogenital hiatus which contains the urethra in the male.

05:29 The urethra and the vaginal canal in the female.