So what does small intestines look like?
Well what we can see if we open up the
abdomen for the first time. If you are
going to the dissecting room and you open up
the abdomen and you remove the flaps
of anterior abdominal wall. What you met with
is actually an apron like structure.
An apron like structure which we can
see here is and that's hanging down
from the transverse colon.
Transverse colon would come
later on but that's part
of the large intestine
and actually dangling down from
the large intestine is this apron fatty
membrane which is known as
the greater omentum. We will cover this
in more detail.
If however we move across onto
this diagram on the other side
and we have actually elevated
the transverse colon and we have
elevated the greater omentum we can
see we have the coils of intestines.
Now here we can't see the duodenum
but we can may count the jejunum
and we can may count the ileum. The jejunum
move in this upper left quadrant
and the ileum down in this lower right
quadrant as it is continuous with the
large intestine. Here we can see the ascending
colon and that's going to be taking food
up in this direction. So it starts up here where
we have got the stomach deep to these elevated
structures. And then it’s going to pass generally in
this direction towards the large intestine
where they are going ascending colon we got the
transverse colon that will sweep down towards the rectum
we will cover this later on. So we open up
the abdomen in the cadaver,
and the first thing you see is the greater omentum.
Reflex in the greater omentum reveals
the small intestine.
So if we now look in these cartoons we can see that
we have actually mobilized the small intestine.
So we have mobilized the small intestine and we
have pushed it to the right side on this diagram
over here. And on the opposite diagram we can
see we moved over to the left hand side
and by doing that, we can still see the
various features. So over here we can see the
ascending colon. We can see the transverse colon
and then because we have mobilized it to the right
we can see the descending colon and the sigmoid colon.
We will cover these in more details
in more detail later on.
But we can see where we flipped over to the
right hand side, we can see the beginning
of the jejunum. And this is
known as the Duodenojejunal junction.
We can see here, we have
got the "C" shaped part, this
bottom of the "C" shaped, remember the duodenum what we
assume in this position, but is posterior to the transverse colon
So we can see that the duodenum would be coming
around in here. In just in this portion we can see is the
horizontal part of the duodenum.
This is then going to be continuous
with the jejunum and the duodenum
is continuous with the jejunum
at this region here which is
the Duodenojejunal junction.
And we can pick that up here. The jejunum
is then going to be continuous all the
way with the ileum. And then we going to pick
the ileum up as it progresses towards
the ascending part of the colon,
part of the large intestine.
So we can see the small intestine,
now that we have mobilized it
can actually pass from
the upper left quadrants
all the way down to the lower right
quadrant. And what we can see is the
small intestine, especially the
jejunum and the ileum is mobile.
We can actually physically lift it
up and move it around the abdomen.
We can't do with duodenum. We can't do with
the other organs like the pancreas or the kidneys.
And that's because the small intestine
is suspended within the abdomen
by a layer of the peritoneum and
this is known as the mesentery.
We will cover the peritoneum in later
lectures. But for now we can appreciate
that the small intestine,
the jejunum and the ileum
is suspended from the posterior
abdominal wall via the mesentery.
A layer of peritoneum that extends
with the posterior abdominal wall.
If we then look at this other picture,
we have actually removed the small intestine from
the abdominal cavity. You release the majority of
the small intestine from the abdominal cavity.
And here we can pick up the stomach and
then we have got the "C" shaped duodenum.
Remember the duodenum is what
I said as retroperitoneal?
So we have removed the jejunum and the ileum.
And when we have passed the large intestine
and we can now see
the "C" shaped duodenum.
We have then got this part of the duodenum
which is going to be continuous with the jejunum
so there we have the Duodenojejunal junction.
This is up in the upper left quadrants of the abdomen.
And then we can see this root of the mesentery
that's where the mesentry is going to
fan out and attach to the small intestine
The small intestine is then going to be
continuous with the ascending colon over
the large intestine. And we can see
that on this diagram on the opposite
side. We can see the
distal ileum is continuous
with the large intestine and this
occurs at the ileocaecal junction.
We can see that the ileum is then progressing
and entering into the large intestine
through the ileal orifice and there
we can see the ileocaecal junction.
We can see below the junction, we have the caecum,
and then above the junction we have the beginning
of the ascending colon.
So we can see from the stomach to the
duodenum around the jejunum and ileum
towards the large intestine.
Where the ileum then opens up
into the large intestine. The caecum,
inferiorly; the ascending colon, superiorly.