Now we want to understand the elements of the
abdominal wall. There are skeletal elements
as well as muscular elements. This slide highlights
the skeletal elements that define the abdominal wall.
And we will start in the anterior midline at
the level of the xiphoid process. So that is
one of the skeletal components. We will work our
way along the rib cage and the costal cartilages
that we see along here constitute the costal margin.
So that also represents skeletal components
of the abdominal wall. We will then encounter the
tip of the eleventh rib and then the twelfth rib
will also help to define the skeletal elements.
We can see the twelfth rib here posteriorly
in greater detail. We'll also have the lumbar
vertebrae. L1 down to L5. The intervening
intervertebral disc will help constitute the wall.
We have the ilia. Right and left. And it would be
the area above this particular line, standing
above. Those help to define the abdominal wall.
So it would be that wing like extensions of the
ilia. We also have the superior aspect of your sacrum
that we see along here but not below. Now we're
getting into the pelvic cavity and these then
will be the skeletal components. You'll note that
we have gaps between these skeletal elements.
We have a gap between the twelfth rib down to the
wing of the ilium. And that is a bilateral gap.
We will fill that gap in with muscular components
to the wall. We also have a gap here anteriorly
and laterally down toward the pelvis. We will fill
that large gap also with muscles. That then brings us
to the muscle elements of the wall where we'll
have posterior muscles and we'll have anterolateral
muscles arranged as flat muscles and vertical
muscles. Our posterior wall muscles are shown
in through this area and also on the opposite side.
These posterior wall muscles quickly include the
quadratus lumborum, the psoas major, this
smaller muscle which you'll see the belly here.
And then a longer tendon. This is the psoas minor.
This one may be absent. And then we also have the
iliacus as seen in through here. For our
anterolateral muscles, again we'll divide those
into flat muscles and vertical muscles. We can see
our flat muscle arrange in here. We'll have three
pairs of flat muscles. This represents the
external abdominal oblique. Over here,
the external abdominal oblique has been cut
along this edge and along its aponeurosis here.
We also have vertically oriented musculature.
This is your rectus abdominis. These areas here
represent your tendinous intersection. Linea
semilunaris, lateral margin of the rectus
represented here. And your linea alba is represented
down the midline through the umbilical region.
The last vertically oriented muscle which may be
absent is the pyramidalis. And it is bilateral.
So you have a right one and a left one.