Okay let's start off our discussion with the uterus in terms of talking about its
three main functions so in no particular order this is going to be the source of menstruation
flow and we'll talk about which particular layers of the uterus will provide this it is
also the site of implantation of a blastocyst and lastly this is going to be where the fetus will
develop during pregnancy so fetus development so as you can see it's very dependent on what
is going on per month if there is implantation and fertilization then there'll have be very
different functions as opposed to just typical menstruation monthly menstruation so we'll talk
about those and a bit more detail as we move on but first let's talk about the different parts
of the uterus we're going to start with the most superior portion which is the fundus in
which you can see about the fundus is it's this area that's superior to the uterine tubes or
where the uterine tubes attached to the uterus where you have the entering there and that's
really important in terms of understanding in which direction or which tilt the uterus
has so we'll talk about the fundus in a bit more detail there the majority of the uterus
is referred to as the body so all of this right here is considered the uterine body the isthmus
similar to what we had with the uterine tube is kind of this pinched in area of the narrowing
portion of the uterus that leads into the cervix and the cervix is going to be the most inferior
portion of the uterus this is one of the more immovable it's very fibrous in comparison to
the rest of the uterus which is mostly muscular but we have a lot more fibrosity associated
with the cervix that's why you can palpate the cervix in some type of digital exam but
you're not necessary able to do so with the more muscular portions of the the rest of the uterus
now let's talk about the hollow portions of the uterus the majority of the lumen is referred to as
the uterine cavity so this portion right in here that will lead into the cervical canal now we're
going to talk about the internal and external os in just a minute but before we move on to that I want
to talk about the organization of the uterus in relation to the bladder and the rectum so
if we're looking here this is going to be more anterior this is going to be more posterior you
can see the uterus is kind of right here in the middle the bladder is going to be located here
and the rectum is going to be located here so it's right kind of in the in between the bladder
and the rectum dependent on how full the bladder is that can change the position of the uterus and
one thing I want you to note here will bring this picture back up again in a second that you have
the majority of the body and in particular the fundus of the uterus that's going to be tilted
more anteriorly now let's look at another image to talk about the internal and the external us
so internal os here this is the uterine cavity entering into the cervical canal so it's kind
of that that space or that entryway into that whereas the external os is that cervical canal
entering into the vagina and so you have these two different areas you talk about them differently
or clinicians will discuss those separately to make sure we understand those terms okay so we
kind of introduced the term flexion when you're describing the direction of the uterus and so
you'll have two real ways that you discuss this a -flexion as well as -version so let's start
with -flexion first and what we are really focused on when you're talking about flexion is the angle
between the body of the uterus so the uterus here and the cervix so in which way it is angled anteflexion
you have it more anteriorly placed so the body of the uterus is going to be kind
of tilted that way whereas retroflexion you'll have the body of the uterus more posteriorly tilted
anteflexion is the more typical presentation in terms of the uterus then you'll hear the terms
antiversion and retroversion these are different than the flexions that we just discussed here and
what we're focused on here is the angle between the cervix and the vagina and the vagina is going
to be this right here anteversion you're going to have the cervix more anteriorly placed and
this is the more typical presentation and retroversion you'll have a more posterior tilt so antiflexed antiverted uterus is the most typical presentation well if there's a retroflexion or
a retroversion it's not necessarily symptomatic or troublesome sometimes you can have a prolapse
associated with retroversion but not necessarily so now ligaments associated with the uterus we've
been talking about this broad ligament will kind of finish it up now so let's review really quickly
those three parts of the broad ligament you have your mesosalpinx and think about it try to
remember where is what is this associated with it's gonna be associated with the uterine tube
you'll have your mesovarium which is going to be associated with the ovaries and then you'll
have your mesometrium and that's kind of the the bulk of the broad ligament so all of this
yellowish shading right here around the uterus that's going to be the mesometrium so plays a
very big role in terms of anchoring and keeping that uterus associated with the lateral wall also
important to note broad ligament is peritoneal in origin now also of great importance is the
cardinal ligaments and this serves as the main passive source of protection of the uterus and the
vagina and it's attachment to the pelvic wall this is a very fibrous part of the ligament so a
lot of times if you have sutures related to this region associated with surgeries a lot of times
you can go through the cardinal ligaments because those are tough enough as opposed to peritoneal
linings like the broad ligament and then lastly we have the round ligament and you can see the
round ligament right here the round ligament is like the ovarian ligament we discussed previously
this is a remnant of that gubernaculum the round ligament is an attachment of the uterus
all the way to the labium majora so important in terms of keeping it tethered in that region
so you have enough flexibility to have the uterus move some particularly compared particularly with
the filling of the bladder but enough to keep it in its place particularly during pregnancy all
right so let's talk about the layers of the uterus and we'll start with the outermost layer which is
your perimetrium so you often hear this referred to as serosa and really what's important here is
this is part of the peritoneum and you're gonna have an association of the peritoneum with the
other organs in this region for the vesico-uterine pouch and the recto-uterine pouch and let's look
at a picture of this I think it'll give you a better idea of what we're talking about alright
so all this kind of shiny stuff that you see in this picture is covering the organs in this
region so let's start with finding the uterus the uterus is going to be located right there
and then your urinary bladder is right here so that peritoneum is just going to kind of
lie on top of those two structures and then the bladder and the uterus are going to be located
underneath that region so that space that little pouch formed in the middle is referred to as the
vesico-uterine pouch so vesico- you know we're talking about the bladder then you're gonna have
the rectum back in this region so the recto-uterine pouch which is similar in terms of be
just a peritoneal pouch in this region it's going to be quite a bit deeper as you can see from this
image than the vesico-uterine pouch and this is closely related to the fornices of the vagina
and we'll talk about those and more specifics when we talk about the vagina but this is going to be
the more clinically relevant pouch so the recto-uterine as we move deeper we're getting to the
myometrium anytime you have the term myo- you know we're talking muscle and so you have three layers
of smooth muscle these will contract during labor in order to help expel the fetus it can also
contract during the menstrual cycle and you get what's referred to as cramps so this is going to
be the the middle layer it can change dramatically depending on what's going on with the uterus so
during pregnancy and when there's a fetus you will have a great extension but thinning of the muscle
in this region then lastly the deepest layer is the endometrium which is particularly important
in terms of the menstrual cycle this is highly highly vascularized and so that makes sense when
you're thinking about menstrual flow and there's two main parts of the endometrium there's the
stratum functionalis this is the part that will sloth off during menstruation and then the stratum
basalis which is always the permanent layer it will help the formation of the stratum functionalis
after the menstrual flow endometriosis is a disorder where you're going to have endometrial
tissue formed outside of the uterus okay so you can have it in the peritoneal cavity you can have
it associated with other organs and pelvic cavity and what happens with this endometrial tissue is
that it will be affected by the hormones and that no matter where it's at so if you have the release
of hormones around the the menstrual cycle time then you're going to have the vascularization
the engorgement of that blood in that region and you can have bleeding in areas where you wouldn't
typically have it during the typical menstrual cycle now the arterial supply of the uterus is
the uterine arteries and these are going to be branches of the internal iliac arteries remember
if we kind of trace our way back in terms of the internal iliac internal iliac is a branch of the
common iliac and the common iliacs are going to be at that bifurcation of the aorta so there's
your abdominal aorta common iliacs and then those common iliacs will divide into the external
iliac and the internal iliacs so pretty much everything that we're talking about with pelvic
organs are going to be supplied by branches of the internal iliac other than the ovaries which
we know are going to be direct branches from the abdominal aorta one last thing i want to note is
talking a little bit more about the cervix and we'll bring this back in a further discussion
but that cervix is going to be the most immobile portion of the uterus it's going to be the most
fibrous or hardest portion of the uterus so you can palpate the the cervix through a digital exam
what's also unique about this the cervix is you're going to have the secretion of cervical mucus and
this change is dependent on at what point in the the the menstrual cycle you're in so if you're
menstruating or you're ovulating this will be a little bit less it'll be a little more fluid than
you would have in other types of the cycle so you had these secretory cells within the cervix
for this specific for the specific secretion of this mucus so we've kind of understood the
overall organization of the uterus we've talked a little bit about the layers of that we're going
to continue inferiorly to the vagina in order to lead to the discussion of the external genitalia