If we carry on looking at the vagina, then deep
within the vagina as it is approaching
the cervix, we find a region known as the
fornix and that's this region here
which essentially as a gutter-like
structure. A gutter-like
ring that surrounds the cervix which is
protruding into the vault of the vagina.
Protruding into the actual cavity of the vagina.
And here we can see in this diagram
we have what's known as the external os
and that is a small opening which we can see here as well.
The opening that is continuous with the
cavity of the uterus and the vagina.
And we can see the cervix
this region here, is actually pushing
into the vagina, this region
just here. And as it pushes in, it leaves
a gutter that surrounds the cervix.
And this gutter which we can
appreciate is around here
here we have the wall of the vagina
here and here is known as the fornix.
And we can recognize
four parts to a fornix.
We can have an anterior portion
a posterior portion
and two lateral portions.
So this is the anterior aspect of
the fornix. This is the posterior aspect.
And around the sides of the cervix,
we will found the more lateral,
so deep within here, we find
the lateral aspect of the fornix.
But this is a continuous gutter most
like a moat that surrounds a castle.
We have mentioned previously that
the posterior fornix is the deepest
of these fornices. And it’s important because
it is closely related to the rectouterine pouch.
And I have mentioned previously that the
rectouterine pouch, this peritoneal pouch here
is deep and free fluid and pus
can collect in this region.
Access to this pouch is best
served by passing through the vagina
and through the posterior fornix and we
can see it passing through in this direction.
So transvaginal approach through
the vagina, through the posterior fornix
to drain free fluid or
pus from the rectouterine pouch.