hello anatomy colleagues this is dr alsup and in this video we will be discussing the pelvic
diaphragm and it makes sense to be talking about this in this session as it forms part of that
inferior boundary of the true pelvic cavity so our main goal here will be to outline the muscles or
the muscular contents of the pelvic diaphragm so the basic placement of these muscles but really
quickly i do want to make sure to point out that the pelvic diaphragm is more than just the muscles
but also that investing fascia that surrounds the muscles so oftentimes you see an image like this
it looks like it's almost all muscles but there's certainly investing fascia that's surrounding it
in that superior investing fascia the portion that's facing the internal pelvic viscera is
going to be thicker than what would be on the inferior portion so that combination of the two
fascial layers and of course the muscles will form what is considered the pelvic diaphragm
okay so you can think of the pelvic diaphragm as kind of the bottom of a bowl and within the bowl
so i'm just kind of outlining the basic portions that are considered part of the pelvic diaphragm
maybe a little bit too anterior here but you get what i'm saying
so it's kind of the bottom of the bowl within the bowl would be the internal pelvic viscera
such as the bladder the uterus the prostate and the rectum so thinking about the place placement
of this area you can infer function which includes supporting that pelvic viscera that i just named
resisting intra-abdominal pressure it's also going to play an important role in terms of urinary and
anorectal continence these muscles also must relax to an extent to allow urination and defecation
just to name a few functions there will also be a medial hiatus of the pelvic diaphragm you can see
it kind of bracketed right here that allows for pelvic viscera such as the urethra the anus the
the vagina to pass towards the perineum and this area is often referred to as the urogenital hiatus
but you may also hear the term levator hiatus and they're both indicating just basically that
area that allows for viscera to traverse so if you are looking on the other side so the more inferior
or superficial side this is a superior view so looking into the pelvic cavity
so if you're looking at the opposite side or that inferior side you would be looking at the perineum
and the perineum is going to be one of the major focuses of the next session
so let's talk big picture regarding the muscles that make up the pelvic diaphragm
are going to be two main muscles you will have the levator ani muscle and you'll have one kind of on
each side and then the coccygeus often also you hear referred to as the issue coccygeus and so
when you bring have these two muscles together that is going to be the pelvic diaphragm muscles
and again we're looking at a superior view here same thing as here so you're looking into the
pelvic cavity with all the viscera removed because if the visceral were present that would mostly
occlude the view of the pelvic diaphragm these other muscles that you can see here
are going to like the piriformis or the obturator internist muscle are going
to be considered parts of the walls of the pelvis and not part of the pelvic diaphragm
the levator ani muscle is often subdivided into separately named portions according to the
pelvic viscera to which it is related and also its attachment points but i want to point out
that they are very much continuous and often difficult to differentiate the boundaries
between where one part begins and the next part starts the puborectalis muscle i'm going to put
an r here to indicate that tends to be the most medial and will have an anterior attachment to the
pubis bone and will meet with its contralateral counterpart to form a sling around the rectum
puborectalis is sometimes just considered a component of the pubococcygeus muscle in fact you
see it's not even labeled on this image it's just considered part of pubococcygeus during a vaginal
birth these most medial portions of the pelvic diaphragm are most at risk of damage or tearing
the pubococcygeus which you can see next here so i'm going to put the i'm going to put a p here for
that pubococcygeus is um is going to also attach to the pubis as well as to this uh condensation of
obturator fascia which you can see really clearly here in terms of this white portion this is called
the tendinous arch of levator ani i just want to note this because it's usually grossly visible
and again you may have pubococcygeus further subdivided according to pelvic viscera as closest
to so we talked about rectalis again we do want you to be able to kind of differentiate between
these two at least understanding the close relationship to the rectum for the pubertalis
but you may have other subdivisions of pubococcygeus such as pubovaginalis
or puboprostaticus but there's a lot of variability in those naming schemes so we
don't expect you to know those two that i just mentioned just in case you hear it elsewhere
uh the excuse me i should have put this right here this is the pubococcygeus
um this will be the iliococcygeus here so i'm gonna put a big I make it like a super
thick I right here whereas the the pubococcygeus will be here and again you would kind of
combine these into one pubococcygeus with the puborectalis being a component of that
so iliococcygeus is going to be a bit more posteriorly placed but it will be anterior
to the coccygeus muscle so closely related to the pubococcygeus and still considered a
part of the levator ani so iliococcygeus will be the most posterior portion of the levator
now the ischiococcygeus is going to be the most posterior portion of the entirety
of the pelvic diaphragm so iliococcygeus is most posterior of the levator ani but the coccygeus
muscle tends to be considered its own muscle and it will be the most posteriorly placed
uh it's also a bit more superiorly positioned than the rest of the pelvic diaphragm so there's kind
of like a superior tilt in that muscle this muscle in illustrations and even in some blue link images
looks pretty muscular it looks like there's a lot of muscle fibers there but it's actually typically
almost completely tenderness meaning they're very few visible muscle fibers it looks like
a sheet of tendon quite often so this is a little misleading in terms of how thick the muscle looks
alright so that is it very foundational understanding of the basics of the pelvic
diaphragm and of course here is our handy dandy summary slide again noting levator ani looks like a
continuous sheet of muscle with the very closely associated coccygeus muscle so iliococcygeus
the pubococcygeus and the puborectalis
would be levator ani coccygeus also part of the pelvic diaphragm and then these other muscles
here would be considered the wall uh part of the walls of the the pelvic cavity all right so please
take your time to review and thank you for your time and attention have a great rest of your day