00:01
The next muscle we'll look
at is internal oblique.
00:04
And that is situated deep
to external oblique.
00:07
If you remember from
the previous slides.
00:09
An internal oblique
has a large number
of bony attachments,
origins, and insertions.
00:15
So we can see those
on the screen here.
00:17
So most posteriorly we see on the
left hand side of the screen there.
00:21
We have the thoracolumbar fascia,
we also have the anterior
aspect of the iliac crest,
and the lateral third of
the inguinal ligament.
00:28
And these are all areas where
internal oblique muscle
originates from.
00:33
And you can see by the
direction of the arrows,
it's moving up towards the ribs
and cartilages 10 through to 12.
00:40
So again,
there may be some variation
in depending
on the textbooks you have.
00:44
But typically,
the internal oblique muscle
will insert onto the ribs and the
costal cartilages of ribs 10 to 12.
00:53
You can see it actually
passes up by these green dots.
00:56
And it doesn't necessarily run
perpendicular to external oblique,
the upper fibers which you can see
running upwards,
those very much do run
perpendicular to external oblique.
01:07
But as we go to the inferior
aspect of the muscle belly,
you can see those fibers,
importantly curve anteriorly
and curved towards
the pubic tubercle.
01:18
And we'll come to that
in more detail later on
when we look at the
inguinal region.
01:22
Similar to external oblique,
the muscle of
internal oblique gives rise
to a thin tenderness flat sheath
and this is the aponeurosis.
01:31
So again, we can see the
aponeurosis here of internal oblique
is running towards the midline,
where we have the linea alba.
01:38
And this forms an important union
with the aponeurosis
of external oblique.
01:43
And again, we'll come to
that in a moment or two.
01:46
The function of internal oblique
is again to help with
bending of the trunk.
01:50
You can see on the
screen at the moment,
so the left and the right
aspects of internal oblique
will help with that
left and right bending.
01:58
Again, they help to compress
the abdominal contents
help them to maintain possession.
02:02
And also when both of the
internal oblique muscles contract
so you'll have
flexion of the trunk.
02:09
The third of these lateral muscles
that we want to talk about
is transversus abdominis.
02:15
As you can see on
a similar diagram,
the origins and insertions of
the transverse abdominis muscle
are similar coming from similar
regions that we've already seen.
02:24
So posteriorly,
we have the thoracolumbar fascia,
we have the iliac crest, inferiorly,
and then superiorly,
we have the inner surface of now
7 through to 12,
costal cartilages.
02:36
So we can see we have the
origins of that muscle.
02:39
This time, as we spin it
round to the anterior aspects,
let's just do that slightly.
Again, you can see the green arrows
are really indicating the
transverse nature of this muscle.
02:49
A reason I haven't indicated because
we can see it now as it rotates
is that these muscle also goes on
to the lateral third
of the inguinal ligament,
and we'll come back
to that later on.
03:00
So it's good to see
that transverse nature
of this muscle
transverse abdominis,
as it causes around anteriorly
onto the abdominal wall.
03:09
But you can see now how it runs
anteriorly towards the midline,
where again,
it unites with the linea alba.
03:16
And again, those green arrows
are indicating the aponeurosis
of this transverse
abdominis muscle.
03:22
So here we can see the linear alba.
03:26
The function of this muscle very
similar to what we've seen before
compression of abdominal contents.
03:31
And it can also help
when those muscles contract
to helpfully rotate the
abdomen as round as well.
03:36
So out rotate the trunk.