So, the pelvic floor. The pelvic floor is a muscular
floor. It forms the inferior boundary of the
pelvis. It’s made up of a series of thin,
flat muscles. And if we look here, we can
see that similar to the last diagram, the
organs, the blood vessels are being removed
and we have just got the musculature. We can
remind ourselves of some of these muscles.
We have piriformis here, have piriformis from
the anterior surface of the sacrum and that’s
going to pass out via the greater sciatic
foramen. We also have coccygeus muscle here,
sometimes known as ischiococcygeus because
it’s passing from the coccyx to the ischium,
you can see that here, coccygeus running on
the inside of the sacrospinous ligament.
We then find we have obturator internus muscle.
Here is obturator artery, nerve and vein passing
through the obturator canal. And here, we
have that thickening running from the superior
pubic rami to the ischial spine. We have that
thickening of obturator membrane and that
is a tendinous arch. Running medially from
this tendinous arch, we have our pelvic floor
muscles. See them radiating from this tendinous
arch laterally running towards the midline.
At the midline, they are going to be met by
the pelvic floor muscles that have come from
the opposite side and they form this hammock
from one tendinous arch on the left to one
tendinous arch on the right. They form this
hammock that fills the floor of the pelvis
running from the tendinous arch into the midline.
We can see that in slightly more detail when
we add in the specific muscles that form the
pelvic floor. But, this pelvic floor is, like
I have said, a funnel shaped pelvic diaphragm.
Remember, the diaphragm separates the thorax
from the abdomen. Now, we have a pelvic diaphragm
again formed by a series of thin, flat muscles
that is going to separate the pelvis above
from the perineum below. So, it’s a partition.
Just like with the diaphragm, you had apertures
to allow the oesophagus, the inferior venacava
and the aorta to pass through. This pelvic
diaphragm also has apertures that allow the
anal canal, the urethra and in the female,
the vagina to pass through.
We can see some of these here.
So, the pelvic floor, the pelvic floor itself
is thin sheets of muscle originating from
the tendinous arch is made up of what we call
levator ani and coccygeus muscle. We are familiar
with coccygeus muscle, we can see that here.
We then have a series of three muscles that
form levator ani. We have puborectalis, we
have pubococcygeus and we have iliococcygeus
and these three muscles form the pelvic floor,
if coccygeus is added. So, puborectalis, pubococcygeus,
and iliococcygeus are levator ani; levator
ani plus coccygeus is the pelvic floor.