00:01
and leg flexion. Now let’s turn to the superior
gluteal nerve. The superior gluteal nerve
passes out superior to the piriformis muscle,
which we can see here. So it passes out above
piriformis, and it’s going to pass out and
supply importantly, gluteus medius and
gluteus minimus. And that’s what we can see here,
the nerve supply to these muscles from the
superior gluteal nerve. So if we were to have
damage to the superior gluteal nerve, then
the superior gluteal nerve supplying gluteus
medius and supplying gluteus minimus, these
muscles are involved in keeping the pelvis
level when the contralateral limb is elevated.
00:44
So that if the superior gluteal nerve, we
can see it here, is damaged, these two muscles
are going to be paralyzed. And when the patient
stands on one leg, when the patient stands
on one leg, the leg that is standing, these
gluteal muscles contract, and that stabilizes
the pelvis. So when you’re standing on one
leg, that leg is fixed. Gluteus medius and
gluteus minimus will contract, and that will
pull the pelvis level. If gluteus medius and
gluteus minimus are paralyzed, then that muscle
cannot hold the pelvis level. So it all drops
to the opposite side. The pelvis would drop
to the opposite side that gluteus medius is
damaged. And this is known, when you’re asked to
stand on one leg, as a positive Trendelenburg
test. You ask the patient to walk, and if
you have drooping of the pelvis, it indicates
that the superior gluteal nerve may be damaged,
and gluteus medius and minimus may be paralyzed.
01:53
When the patient is asked to walk, they may
compensate with a gluteal limp or waddling
appearance as they try to compensate movement
of the body to the affected side.
02:04
So they may have this waddling appearance as they’re
trying to walk. Here, we can see how the gluteus
medius and gluteus minimus muscles will contract.
We can see them here. So that with this leg
being fixed, contraction of this muscle is
going to shorten this distance here and here,
and that’s going to have the effect of tilting
the pelvis upwards. So the pelvis then stays
leveled. Remember now, this leg is fixed because
it’s on the floor. It’s not elevated like
this leg. So when the gluteus medius and minimus
contracts, it’s going to pull the iliac
crest downwards, which is going to maintain
the level of the pelvis. With this muscle
in this diagram being paralyzed, then you’re
not going to pull the iliac crest downwards.
02:57
It’s going to be allowed to fall as this
leg is no longer supported because it’s
been elevated, and the pelvis will now fall
down to the unaffected side, the side opposite
paralysis of the gluteus medius muscle. And
we can see that you’ll have this waddling
appearance, so you’ll try and move your body
across to the supported leg as you try
and walk. Now let’s turn to the common fibular
nerve, and we know the common fibular nerve