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.
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.
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
So, let's just do that once more. What we
can see is that we have the midline here.
We have apertures in the midline known as
the urogenital hiatus, the anal hiatus here.
These allow in the female, urogenital hiatus,
the urethra and the vagina to pass through.
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.
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.
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.
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.
So, the function of these pelvic floor muscles
is really important and remember, we have
levator ani and we have coccygeus.