Lower limb venous physiology and function

• The lower limb venous system overcomes gravity to return blood to the heart.
• Calf muscle pump and the vein-valve system accomplish this efficiently.
• Superficial veins function as principal collection system, dilating to accommodate large volumes of blood from tissue and skin before draining to the deep system for return to the heart.

The 2 major veins of the superficial system namely the Great Saphenous and Short Saphenous (GSV and SSV).

• GSV originates medially from the dorsal vein of the foot and continues proximally along the medial aspect of the calf and thigh before joining the deep vein at the sapheno-femoral junction.
• An anterior accessory is common in up to 14%
• SSV originates inferior and posterior to the lateral malleolus, ascends the posterior aspect of the calf between the gastrocnemius and heads to the popliteal fossa.
• In 60%, it drains into the deep popliteal vein at the sapheno-popliteal junction located within 5-7cm of the popliteal skin crease.
• In the remaining, the SSV may drain into other veins such as the GSV or have several termination points.

Chronic Venous Insufficiency (CVI) and Varicose veins (VV)

Primary venous disease occurs as a result of focal or diffuse structural weakening of the vein wall. The exact nature and cause are not completely understood. Valvular incompetence in the superficial veins can occur due to disruption by thrombotic events, be congenitally absent, atretic or dysfunctional over time.