Venous Drainage of the Lower Limb

Question 1

Deep veins of the lower limb

Answer 1

Deep veinage drainage system is located beneath to the deep fascia. As a rule of thumb, the deep veins share the names of the artery they accompany. Often the artery and vein is located within the same sheath - arterial pulsations aid venous return.

The foor and leg

Doral foot - dorsal venous arch - drains into superficial veins - some penetrate the leg to form the anterior tibial vein.

Plantar foot - medial and lateral plantar veins arise. These veins combine to form the posterior and tibial and fibular veins. The posterior tibial vein accompanies the posterior tibial artery, entering the leg posteriorly to the medial malleolus.

Posterior surface of the knee - the anterior tibial vein, posterior tibial vein and fibular veins combine to form the popliteal.

The thigh

Once the popliteal vein has entered the thigh, it is known as the femoral vein. It is situated anteriorly, accompanying the femoral artery.

The deep vein of the thigh (profunda femoris vein) is the other venous structure in the thigh. Via perforating veins, it drains blood from the thigh muscles. then empties into the distal femoral vein.

The femoral vein then leaves the thigh by running under the inguinal ligament, at which point it is known as the external iliac vein.

The gluteal region

Drained by the superior and inferior gluteal veins - these empty into the internal iliac vein.

Question 2

Clinical relevance: deep vein thrombosis

Answer 2

Formation of a blood clot deep within the deep veins of the lower limb, causing blockage of a vessel. Locally, this cause pain, swelling, and tenderness of the affected limb.

The main complication of a DVT is a pulmonary embolism. The thrombus becomes disloadged and travels into pulmonary circulation. Pulmonary blockage prevents blood returning to the heart - this is known is known as mechanical shock.

High risk patients of DVT undergo prophylactic treatment to prevent thrombosis.

Question 3

Superficial veins of the lower limb

Answer 3

These run in the subcutaneous tissue. There are two major superficial veins:

1) Great saphenous vein - formed by the dorsal venous arch of the foot and the dorsal vein of the great toe. It ascends up the medial side of the leg, passing anteirorly to the medial malleolus and posterior to the medial condyle at the knee.

As the vein moves up the leg, it receives tributaries from other small superficial veins. The great saphenous terminates by draining into the femoral vein, immediately inferior to the inguinal ligament.

2) Small saphenous vein - formed by the dorsal venous arch and the dorsal vein the little toe. It moves up the posterior side of the leg, passing posteirorly to the lateral malleolus, along the lateral border of the calcaneal tendon. It moves between the two heads of the gastrocnemius muscle and empties into the popliteal vein in the popliteal fossa.

Question 4

Clinical relevance: varicose veins

Answer 4

In the lower limbs, blood drains from the skin into superfical veins, and then into deep veins.

Within the veins are valves that prevent backflow of blood. If the valves become incompetent, blood flow can come back into the superficial veins, resulting in increased intra-luminal pressure, which veins cannot withstand. These veins become dilated and tortuous - this is known as varicose veins.

There are changes that occur in varicose veins. Pressure of the venous system rises. This damages the cells, causing blood to extrude into the skin. Further complications can result in ulceration and brown pigmentation of the surrounding tissue.

Treatment:

1) Vein ligation, stripping and avulsion
2) Foam sclerotherapy - injecting an irritating substance into the varicose vein - inflammation occurs, closing off the vein.
3) Thermal ablation - heating the vein from inside (via radiofrequency or catheter lasers, causing irreversible damage to the vein, closing it off.