Venous Drainage – Lower Limb: Superficial Structures and Cutaneous Innervation

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