The lower limb contains an intricate network of veins that traverse between superficial and deep planes. In many aspects, the veins are often overlooked and are considered less important than arteries. However, if one were to look at different clinical conditions, there is a great deal of venous disease that can accompany various clinical conditions. From simple aspects such as the flow of blood to more complicated areas of venous flow such as the muscular pump (the gastrocnemius and soleus) and various functional conduits, venous disease encompasses a variety of different presentations. In order to understand venous disease, it is essential to have a good understanding of the lower limb venous anatomy and pathophysiology. This article deals with this in a bit more detail.
The Venous Anatomy
Broadly classified, the venous system in the lower limbs can be divided into a superficial venous system, a deep venous system and the perforating veins. This division is made in relationship to the various muscular and fascial planes in the lower limb. The superficial venous system lies over the deep fascia while the deep venous system lies underneath the muscular fascia. The role of the superficial system is to drain blood from the cutaneous circulation while that of the deep venous system is to drain the blood from the muscles of the leg. The superficial and deep venous systems are connected to each other through the perforating veins that are run through various fascial planes to establish this connection.
The superficial venous system
The superficial venous system lies just beneath the skin and includes smaller veins such as the reticular veins, the great saphenous vein and the small saphenous veins. From these veins arise different tributaries that supply the different parts of the skin.
The subcutaneous tissue and the skin is drained by the reticular veins. These veins run parallel to the surface of the skin and are clearly visible under the skin in thin individuals. The reticular veins are connected to the remainder of the superficial system or the deep venous system through the perforating veins.
The great saphenous vein is a large grain of the leg that arises on the medial aspect of the foot, runs up the front of the foot and medial aspect of the calf, crossing over at the level of the knee joint and continuing its course along the postero-medial aspect of the thigh. It ultimately joins the common femoral vein in close relationship to the pubic tubercle (Browse N et al. 1988). Within the leg are compartments that divide the great saphenous vein and its associated nerves and arteries from the reticular veins and the tributaries previously described (Somjen GM 1995). The great saphenous vein possesses an anterior and posterior tributary which can sometimes directly join the femoral vein. Smaller veins drain into the great saphenous vein.
The deep venous system
the blood that circulates through the leg ultimately returns to the heart through the deep venous system. There are three systems of this kind above the knee joint and two of them below the knee joint. The popliteal vein forms the largest part of the deep venous system and runs up the back of the knee. It terminates by becoming the femoral vein.
Browse N, Burnand K, & Thomas M 1988. Diseases of the Veins: Pathology, Diagnosis, and Treatment London, Edward Arnold.
Somjen GM 1995. Anatomy of the superficial venous system. Dermatological Surgery, 21, (1) 35-45