00:01
Now let's turn our attention
to the lumbar plexus
but very much look
at it in situ.
00:06
It's very much how it relates
to the numerous muscles
we've spoken about so far.
00:11
So this is a case of
bringing it all together,
we've spoken about the
muscles previously.
00:15
Now let's have a recap by
looking at all the nerves in situ
if we didn't speak to them too
much in the previous lectures.
00:22
So let's have a look
at the lumbar plexus.
00:23
We can see it's coming from T12,
all the way down to L4 here.
00:28
And we can see one of the nerves
that's coming away
from the lumbar plexus
is the iliohypogastric nerve,
this is coming from T12 to L1.
00:37
We have the ilioinguinal nerve,
this is coming from L1.
00:40
And we looked at these nerves
when we looked at the abdominal
wall and the inguinal canal.
00:45
We also have the
genital femoral nerve
coming away from L1 and L2.
00:50
And here we have the lateral
femoral cutaneous nerve
coming from L2, L3.
00:55
Here we have the
femoral nerve, L2, L4.
00:59
And finally, we have the
obturator nerve, L2, L4.
01:03
So it's important to remember
when we looked at
the cutaneous nerve
supply in a previous lecture,
we had that nice even
distribution of dermatomal maps
on the surface of the skin
that very much went alongside
T12, L1, L2, L3, L4, etc,
to give very discreet bands.
01:23
Now we can see how
we have, for example,
the lateral cutaneous
nerve of the thigh
that is covering parts
of dermatome L2 and L3
because it's come from
that spinal cord segment.
01:36
So it doesn't mean if the
lateral cutaneous nerve
is damaged all of L2, L3
dermatome will be lost
because there may well
be some compensation
by other cutaneous
nerves that pick up that.
01:49
So the cutaneous nerve map
and the dermatomal map
needs to appreciate how
they interact together,
but they cover ultimately the
same surface area of the skin.
02:01
Now let's have a look at the position
of the genital femoral nerve.
02:04
It comes from L1, L2
and we can see here
we've got it passing out
through the psoas muscle,
see it's appearing L1, L2,
and then it pierces
the psoas major muscle,
so run alongside its
anterior surface.
02:19
It then gives rise
to a femoral branch,
which goes to supply the skin
over the inguinal triangle.
02:24
We can see here.
02:25
And it also gives rise
to a genital branch
that goes to supply aspects
of the scrotum or the labia
and also motor innervation
to the cremaster muscle.
02:35
So here we can see the
genital femoral nerve
running anterior
to the psoas muscle
and then splitting
into its two branches.
02:43
If we have a look at the
lateral cutaneous nerve,
we can see this
coming from L2 to L3.
02:49
We can see it passing away
and it's running out of the
lateral border of psoas major.
02:54
To run on the surface
of the iliacus muscle.
02:57
It then runs down through
this muscular space
deep to the inguinal ligament,
and it supplies the
cutaneous innervation
on the lateral side of the thigh
highlighted here in green.
03:09
If we look at the femoral nerve,
this is a large nerve.
03:12
It emerges from L2, L3 and L4.
03:15
And as it does so
it comes out again
of the lateral
border of psoas major
and it descends under deep
to the inguinal canal.
03:23
It runs through
the femoral artery
and the femoral vein
within this space.
03:28
It then continues
down and gives rise
to various cutaneous branches
supplies the anterior
aspect of the thigh
and the medial side of the leg
as it runs down distally.
03:38
It also has some motor branches
and its supplies and high
number of muscles in this space
which we can see.
03:45
Principally is surprised most
of the anterior compartment.
03:49
It also supply some
muscles that pass
from the abdomen
down into the thigh
passing through the pelvis
like the psoas muscle
you can see here.
03:58
If we then turn to
the obturator nerve,
obturator nerve comes
from L2, L3, L4.
04:04
It also runs down
within the pelvis.
04:06
This time it's running
medial to psoas major muscle,
and then it exits the pelvis
to enter the thigh via
the obturator foramen.
04:15
So it passes through the pelvis.
04:17
It then exits the pelvis,
enters the medial
compartment of the thigh
to supply the
abductor compartment,
those muscles that help
to abduct the thigh
by passing through
the obturator foramen.
04:29
So as we can see here,
all the muscles in
this medial compartment
are supplied by the
obturator nerve.