Placeholder Image

字幕表 動画を再生する

  • This is a tutorial on the pelvic floor. So what we're looking at here is a superior view

  • into the pelvis. You can see these muscles which make up the pelvic floor at the bottom

  • of the pelvis.

  • So I've got the femurs in here because I've included the muscles of the walls of the pelvis.

  • So you've got the piriformis muscles attaching to the sacrum and to the greater trochanter

  • of the femur. And you've got the obturator internus muscles which you can see here.

  • If I rotate around to the back, you can see the tendon of the obturator internus muscle

  • attaching to the femur. So those two muscles make up part of the walls of the pelvis.

  • So the pelvic floor separates the pelvic cavity above from the perineum below. It consists

  • of the pelvic diaphragm. And then you've got the perineal membrane and the deep perineal

  • pouch.

  • So the word 'pelvic diaphragm' is often used interchangeably for pelvic floor, but in this

  • tutorial, I'm going to talk about the pelvic diaphragm in relation to two specific muscles.

  • And then I'll go on to tell you about the perineal membrane and the deep perineal pouch.

  • So these three structures combined make up the pelvic floor.

  • To begin with, I'm going to talk about the pelvic diaphragm. So the pelvic diaphragm

  • is this dome-shaped set of structures, which we're looking down at. It consists of the

  • levator ani muscles on either side. So you've got this midline raft, this ligamentous midline

  • where the two halves of the levator ani muscle attach. You've got the coccygeus muscle, which

  • is this muscle here.

  • I've just isolated the pelvic diaphragm muscle. You can see the shape of them here. It's like

  • this bowl-shape of muscles.

  • Ignore this extension up here. The muscle doesn't actually extend this far up. Just

  • bear that in mind. So it has its anterior attachment on the posterior surface of the

  • pubis here. And then it attaches along the fascia of the obturator internus muscle.

  • And then at the back, it attaches to the coccyx. And it meets in the midline to form this midline

  • raft. So this is where the levator ani meets in the midline posterior to the anus, which

  • is this aperture here.

  • So anteriorly, you can see that the levator ani muscle has this defect. It's got this

  • u-shaped defect. This is called urogenital hiatus. This allows the urogenital apparatus

  • to pass through the pelvic floor into the perineum below. In males, you've got the passage

  • of the urethra. In females, you've got passage of the urethra and the vagina through this

  • urogenital hiatus.

  • And as you can see, the muscle consists of various different fibers. So you've got these

  • loops of fibers which loop around various structures.

  • So the levator ani muscle is typically thought of in terms of three sets of fibers. You've

  • got the pubococcygeus, which attaches from the bony bit of the pubis and extends back

  • to the coccyx. So you've got the coccyx at back here.

  • And then the anterior fibers of the pubococcygeus actually loop around the prostate in muscles

  • and the vagina in females. So you've got these anterior fibers which are divided and loop

  • around the prostate in males forming the levator prostatae or the puboprostaticus and in females,

  • it loops around the vagina forming the pubovaginalis.

  • And then in the midline as I've mentioned before, connecting from the coccyx down to

  • the anus. So remember, this is the aperture for the anus. So connecting from the coccyx

  • to the anus, you've got this midline raft, this ligament, which is called the anococcygeal

  • ligament or anococcygeal body.

  • And then the next part of the levator ani muscle is this puborectalis muscle. So I'm

  • going to draw this on in green, outline in green. This forms a sling around the distal

  • end of the gastrointestinal tract, so around the sort of anus and rectum, around the anorectal

  • junction. So you've got this sling of muscle from the levator ani forming around the anorectal

  • junction.

  • So these are the intermediate fibers of the levator ani. They again originate on the pubis.

  • They have the important function of maintaining this anorectal angle. So they keep this angle

  • of 90° which closes off the anal canal. And I'll come on to talk about this in a moment.

  • And then we've got the posterior fibers of the levator ani muscle. These are called iliococcygeus

  • muscles or fibers. So you've got these which I'm outlining in purple.

  • So those are the three collections of fibers which make up the levator ani muscle. This

  • muscle forms the bulk of the pelvic diaphragm.

  • So just to quickly recap, the levator ani is composed of these three collections of

  • muscle fibers. If we rotate the model around, you can see the origin of the levator ani

  • on the posterior surface of the pubis and then it's got this origin along the border

  • of the obturator internus muscle.

  • So covering the obturator internus is this fascia and you've got this thickening. So

  • you can see this white thickening. This is a tendinous thickening called the tendinous

  • arch and this is the thickening of the fascia where the levator ani takes part of its origin.

  • And then over here, we've got the ischial spine. So along the spine, from the body of

  • the pubis, along this tendinous arch to the spine of the ischium, the ischial spine, the

  • levator ani takes its origin and it inserts on the coccyx and in the midline at this anococcygeal

  • ligament.

  • So if we just rotate to an inferior view, you can see these muscles taking their attachment

  • on that little coccyx and it's got this perineal body which is a fibromuscular connective tissue

  • node which joins the perineum and the pelvic floor and you've got some convergence of the

  • levator ani muscles on this node.

  • So the function of the levator ani muscle is to support the pelvic viscera and it keeps

  • the rectum and vagina closed. So it has this kind of sphincter closing action on the rectum

  • and the vagina. And importantly, it resists, rises in intrapelvic pressure during any straining.

  • For example, during coughing, when the abdominal muscles increase the intrapelvic pressure,

  • it resists this rise and prevents anything being evacuated from the digestive tract.

  • So one thing I mentioned was the puborectalis maintains the anorectal angle. So you've got

  • this angle between the rectum and the anal canal. The puborectalis loops around this

  • and it keeps this angle. So by maintaining this angle, it forms this valve which stops

  • the anal canal filling with feces from the rectum.

  • So when this muscle relaxes and releases its tension on this angle, the angle between the

  • rectum and the anal canal increases and it becomes more like this, so then you don't

  • get this pinching off of the anal canal and feces can flow from the rectum into the anal

  • canal.

  • So this is important in defecation. You need to be able to relax the pelvic diaphragm muscles,

  • in particular the puborectalis portion of this muscle in order to relax this anorectal

  • angle and prevent shutting off of the anal canal.

  • So the other muscle of the pelvic diaphragm is the coccygeus, which you can see here on

  • either side. So this muscle lies over the sacrospinus ligament. So if I rotate around

  • to the back, you can see this ligament connecting the sacrum to the ischial spine. So it lies

  • over the sacrospinus ligament and it forms the posterior part of the pelvic diagram.

  • It originates on this ischial spine and it inserts laterally on the coccyx in the adjacent

  • margins of the sacrum. If I just rotate around to the back, you can see its insertion along

  • the margins of the sacrum and the coccyx below.

  • So this muscle functions to support the pelvic floor and it's innervated by branches from

  • the anterior rami of S4 and S5.

  • The levator ani is actually innervated by branches of pudendal nerve from roots S2-S4.

  • So you've got that useful mnemonic, 'S234 keep shit off the floor'. It describes the

  • function of the levator ani muscle.

  • We talked about the pelvic diaphragm now in quite a lot of detail. The next part of the

  • pelvic floor is the perineal membrane and the deep perineal pouch.

This is a tutorial on the pelvic floor. So what we're looking at here is a superior view

字幕と単語

動画の操作 ここで「動画」の調整と「字幕」の表示を設定することができます

C1 上級

骨盤底パート1 - 骨盤横隔膜 - 3D解剖学チュートリアル (Pelvic Floor Part 1 - The Pelvic Diaphragm - 3D Anatomy Tutorial)

  • 23 6
    Juan に公開 2021 年 01 月 14 日
動画の中の単語