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of the buttock and the posterior thigh. It
comes from S2 and S3. The sciatic nerve, as
I’ve mentioned, is really important. So I
just want to dwell on it for a second.
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Anterior divisions of the anterior rami from these
nerve roots form the tibial nerve. And the
posterior divisions of these anterior nerve
roots form the common fibular nerve. So here
we’ve got L4, L5, S1, S2, S3. Anterior rami
from these split into these anterior divisions,
and it’s these anterior divisions that form
the tibial nerve. So here we can see the
tibial nerve. We can see coming out here, we got
L4, L5, S1, S2, and S3. And coming from them,
we can see they’re splitting into these anterior
divisions, not these posterior divisions
down here, these anterior divisions here,
and you see another one here, see another
one here. And it’s these anterior divisions
of the anterior rami from L4, L5, S1, S2,
and S3 that forms the tibial nerve. The posterior
divisions of some of these nerve roots, L4,
L5, S1, S2. The posterior divisions, if we
go back to them, see L5 here, is giving rise
to this anterior division and the posterior
division. And this posterior division here,
we see another posterior division here, see
another posterior division here. These are
giving rise to the common fibular nerve. So
these are very similar spinal cord segments
but they’re dividing into these anterior and
posterior divisions. The anterior division
is giving rise to the tibial nerve; the posterior
division is giving rise to the common fibular
nerve; a similar principle that we had for
brachial plexus. The sciatic nerve is the
largest nerve in the body. It’s about two
centimetres wide. As I mentioned, it supplies
the majority of the muscles in the lower limb,
except the gluteal region, the anterior thigh,
and the medial thigh. It’s so big that it
actually has its own artery, and this is artery
to the sciatic nerve. And this artery comes
from the inferior gluteal artery. We’ll
see this when we look at the gluteal region.
So briefly then to finish just the coccygeal