Lower Limb LO5
5. Describe the primary venous drainage of the lower limb.
The veins in the lower limbs have numerous valves to allow for proper directional flow (towards the heart), working against gravitational pull.
Veins are divided into superficial (located in subcutaneous tissue) and deep (accompanying arteries). Superficial veins of lower limbs always drain into deep veins by means of perforating veins.
There are two main superficial veins of the lower limbs:
- The great saphenous vein is formed by the union of the dorsal venous arch of the foot and the dorsal vein of 1st digit, and drains into the femoral v. It can be located anterior to the medial malleolus of the tibia during surgeries.
- The small (short; lesser) saphenous vein is formed by the coalescence of the dorsal venous arch of the foot and the dorsal vein of the 5th digit, and drains into the popliteal v. It is accessible posterior to the lateral malleolus of the fibula.
As mentioned above, deep veins of the lower limb accompany arteries and are often have similar names. These are the major (largest) veins of the lower limb. These veins (which often are paired - venae comitantes) are often packaged with the arteries within a vascular sheath.
Competency of venous valves are vital in directing blood flow in the proper direction. If competency has been compromised (potentially due to rotation or dilation), veins may become varicose. Varicose veins present as a dilated vein with valves that do not close - allowing blood to flow away from the heart.