Venous and Lymphatic Drainage

Contents:

• Introduction
• Deep veins
• Superficial veins
• Varicose veins
• Lymphatic drainage

Introduction

1. Valves. All veins in the lower limb posses valves which are unidirectional.
2. Muscles. Venous return in deep veins (ie those within the muscle mass) is assisted by contractions of those muscles which squeeze the veins. The calf muscles are particularly important - the "calf pump". to be effective this mechanism must be coupled with valves which permit the blood to flow in one direction only.

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Deep veins

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Superficial veins

Venous return in superficial veins is made more efficient by communicating veins which join the superficial and deep systems. These also have valves which permit blood flow from superficial to deep only. Blood flows between contractions of the muscle pump - as the muscle relaxes the pressure in the deep veins drops and blood is "sucked" into them from the superficial veins.

The long (great) saphenous vein is the longest vein in the body. It is one of the 2 best examples of a superficial vein of the lower limb (the other being the short saphenous vein - see below). The long saphenous vein arises from the dorsal venous arch and ascends a little in front of the medial malleolus. It lies a hand's breadth behind the patella and joins the femoral vein by passing through the saphenous opening in the deep fascia of the the thigh.

This is a particularly constant position for a superficial vein and may be used in an emergency for a "cut-down" (ie to introduce a needle or drip, etc) if veins cannot be located in more conventional areas.

The short (small) saphenous vein passes behind the lateral malleolus and up the back of the calf in the midline to join the popliteal vein in the popliteal fossa behind the knee.

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Varicose veins

1. incompetence of the valves in the communicating veins, leading to blood at high pressure in the deep veins passing out into the superficial veins. The walls of the superficial veins distend under this pressure.
2. incompetence of the valves in the superficial veins themselves. The presence of valves traps blood in short segments in the vein. Loss of function in some these veins results in longer segments of blood leading to higher pressures on the walls of the superficial veins.

Varicose veins may be treated surgically, either by tying off leaky communicating veins or stripping out affected sections of the superficial veins.

In the latter case care must be taken not to injure cutaneous nerves which run very close to them ???? ?? the saphenous nerve (a branch of the femoral) or the sural nerve (a branch of the tibial nerve).

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Lymphatic drainage

1. Deep lymph vessels drain all the structures deep to the deep fascia.
2. Superficial lymph veins drain all the structures superficial to the deep fascia.
3. There are more superficial vessels than deep ones.
4. Most of the lymph from the lower limb passes through a terminal set of lymph nodes in the groin (deep inguinal nodes) located around the femoral vein.

1. an upper group immediately below the inguinal ligament.
2. a lower vertical group along the terminal portion of the long saphenous vein.

Deep ??lines of the buttock drain to lymph nodes within the pelvis.

Blockage of the lymph drainage from the lower limb may lead to considerable enlargement "elephantiasis". A cause of blockage in the tropics is by infestations of the lymph vessels by filarial worms.

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