General principles of the structure of the lower limb venous system
The veins of the lower limb are traditionally divided into two major groups: superficial (subcutaneous) veins and deep veins. Superficial veins are located in the subcutaneous tissue and are represented primarily by two large trunks: the great and small saphenous veins. Deep veins accompany the corresponding arteries and frequently run in pairs. There is an extensive network of anastomoses between both systems, ensuring blood outflow under various functional conditions.
Venous blood outflow begins from the distal segments—the toes and the foot—and proceeds proximally into the popliteal vein and further into the femoral vein.
Venous arches of the foot
Similar to the arterial system, two venous arches are formed in the foot:
- Dorsal venous arch of the foot (arcus venosus dorsalis pedis)—formed by the dorsal digital veins and dorsal metatarsal veins.
- Plantar venous arch (arcus venosus plantaris)—collects blood from the plantar surface and drains primarily into the posterior tibial veins.
Along the margins of the dorsal venous arch, two important longitudinal trunks are formed: the medial marginal vein (vena marginalis medialis) and the lateral marginal vein (vena marginalis lateralis). These give rise to the two main superficial veins of the lower limb.
Great saphenous vein
The great saphenous vein (vena saphena magna) is the continuation of the medial marginal vein of the foot. It is the longest superficial vein in the human body. It runs anterior to the medial malleolus, ascends along the medial surface of the leg and thigh, and empties into the femoral vein (vena femoralis) through the saphenous hiatus (hiatus saphenus).
Numerous tributaries empty into the great saphenous vein:
- subcutaneous veins of the anterior and medial surfaces of the leg and thigh;
- external pudendal veins (venae pudendae externae);
- superficial circumflex iliac vein (vena circumflexa ilium superficialis);
- superficial epigastric vein (vena epigastrica superficialis);
- dorsal superficial veins of the penis or clitoris;
- anterior veins of the labia majora or scrotum.
Thus, the great saphenous vein drains a significant portion of the anterior and medial surfaces of the lower limb, as well as the adjacent regions of the anterior abdominal wall and external genitalia.
Small saphenous vein
The small saphenous vein (vena saphena parva) is the continuation of the lateral marginal vein of the foot. It runs posterior to the lateral malleolus, ascends along the posterior surface of the leg, and empties into the popliteal vein (vena poplitea) within the popliteal fossa.
The small saphenous vein collects blood from:
- the lateral part of the dorsal venous arch;
- subcutaneous veins of the sole and lateral margin of the foot;
- the calcaneal region;
- the posterior-lateral surface of the leg.
Between the great and small saphenous veins, there are numerous intersystemic anastomoses, as well as perforating (perforator) veins connecting the superficial system to the deep system.
Deep veins of the lower limb
Deep veins completely mirror the course of the corresponding arteries and are usually represented by paired vessels accompanying the arterial trunk. These include:
- anterior tibial veins (venae tibiales anteriores)—accompany the anterior tibial artery;
- posterior tibial veins (venae tibiales posteriores)—receive the plantar veins and accompany the corresponding artery;
- fibular veins (venae fibulares);
- popliteal vein (vena poplitea)—formed by the union of the anterior and posterior tibial veins in the popliteal fossa;
- femoral vein (vena femoralis)—the continuation of the popliteal vein proximal to the adductor canal;
- deep vein of the thigh (vena profunda femoris)—a large tributary of the femoral vein accompanying the corresponding artery.
The femoral vein, ascending beneath the inguinal ligament, continues as the external iliac vein (vena iliaca externa).
Mnemonic principle and clinical significance
Main mnemonic principle: the deep veins of the lower limb duplicate the course of the arteries, so knowledge of the arterial system automatically provides knowledge of the corresponding venous trunks. The superficial system is memorized separately—via the two marginal veins of the foot and the two main subcutaneous trunks.
Clinical significance: the vena saphena magna is traditionally used for harvesting autografts in coronary artery bypass grafting, while valvular incompetence of the superficial and perforating veins underlies lower limb varicose veins.
Key points
- The veins of the lower limb are divided into superficial (subcutaneous) and deep veins.
- The dorsal and plantar venous arches are formed in the foot.
- The medial marginal vein gives rise to the great saphenous vein (v. saphena magna), and the lateral marginal vein gives rise to the small saphenous vein (v. saphena parva).
- The great saphenous vein empties into the femoral vein via the hiatus saphenus.
- The small saphenous vein empties into the popliteal vein.
- Deep veins accompany the corresponding arteries in pairs (anterior and posterior tibial, fibular, popliteal, femoral, and deep vein of the thigh).
- The popliteal vein is formed by the union of the anterior and posterior tibial veins.
- The superficial and deep systems are connected by numerous anastomoses and perforator veins.