00:00
Now let?s have a look at the venous drainage.
For the venous drainage, we need
to be aware of some valves, and these are
particularly important. We can see the great
saphenous and the short saphenous vein being
the main cutaneous ways that a venous blood
is drained from the lower limb. But we also
can see we have some superficial veins that
lie superficial to the deep fascia and also
some deeper veins and these cutaneous veins,
we can see here, are perforating that fascia.
We can also see that we have these valves.
00:36
So the superficial veins of the lower limb
really are the great and the small saphenous
veins. We can see the great saphenous vein
here, and we can see the small saphenous
vein here. These are draining venous blood from
the lower limb. The great saphenous is formed
from the dorsal venous network on the dorsum
of the foot. It passes through the saphenous
opening in the fascia lata, and it drains
directly into the femoral vein. The small
saphenous is formed from the lateral aspect
of the foot, and it enters the leg through
the deep fascia and drains into the popliteal
vein within the popliteal fossa and we can
see these veins here. If we look at the perforating
and deep veins, then the perforating veins
are going to pass from these superficial veins
through the deep fascia into the deep veins,
and they contain valves. They only allow flow
from superficial to deep. So, blood can?t
flow from deep to superficial. This is important
because, obviously, gravity is against venous return.
01:42
So it prevents the blood from regurgitating
back distally, and blood can only be returned
to the heart. And it?s the valves that do
this. They run obliquely through the
deep fascia. So we can see them passing through
the deep fascia here obliquely and as the
muscles contract, they are compressing them,
and this also prevents retrograde flow of
blood, again, supporting venous return. So if we
look at more detail at the venous drainage
of these superficial blood vessels, the great
saphenous and the small saphenous vein, then
we can see we?ve got this dorsal network
here, this dorsal venous network on the dorsal
surface of the foot. We can see that that is going
to give rise to the great saphenous vein.
02:31
The great saphenous vein, we can see here,
is running from this dorsal venous network
on the dorsum of the foot, and then it?s
running up medially. We can see it?s giving rise
to the great saphenous vein. We can see the
great saphenous vein is then passing up the
medial aspect of the calf. We can see it?s
running up here. It?s going anterior to
the medial malleolus, but then it goes posterior
to the medial condyle of the femur.
03:00
It then passes all the way the medial aspect of
the thigh, and it passes into the femoral vein
by passing through the saphenous opening. So
we can see the great saphenous vein running
up the medial aspect and emptying into the
femoral vein. The small saphenous, this is
coming from the lateral surface of the foot,
so here we can see the fifth digit. So again,
coming from the dorsal venous network, we
have the small saphenous. And this is running,
this time, posterior to the lateral malleolus.
Here we can see, it?s running posterior
to the lateral malleolus, and it?s running
all the way up the posterior calf. It enters
through the deep fascia, and it passes into
the popliteal vein within the popliteal fossa.
03:49
Here, we can see the small saphenous passing
through the deep fascia and go into the popliteal
vein within the popliteal fossa. If we move
on to the cutaneous innervation, then this