True about the anatomy of great saphenous vein: (A) Stas as a continuation of medial marginal vein, (B) Ends as femoral vein 2.5 cm below the inguinal ligament., (C) There are 2-5 valves below the knee, (D) Ascends 2.5 - 3 cm behind tibial malleolus
Answer is A. GREAT SAPHENOUS VEIN:- Lie on the dorsum of the foot. Receives 4 dorsal metatarsal veins. Formed by union of medial end of dorsal venous arch with the medial marginal vein and drains the medial side of great toe.Passes upwards in front of medial malleolus (2.5cm in front), crosses the lower one-third of the medial surface of the tibia obliquely, and runs along medial border to reach the back of the knee.Thigh- it inclines forward to reach the saphenous opening where it pierces the cribriform fascia and opens into femoral vein. Contains 10-15 valves to prevent backflow of venous blood. Incompetence of these valves makes vein dilated and touous leading to varicose veins. The vein is connected to deep veins of limb perforator veins. 3 medial perforators-just above ankle.1 perforator just below knee 1 in the region of adductor canal. The perforating veins are also provided with valves which permit flow of blood only from superficial to deep. TRIBUTARIES:-1. At the commencement-medial marginal vein.2. In the leg- small saphenous vein.3. Just below knee-anterior vein of leg , posterior arch vein, vein from calf 4. In the thigh-accessory saphenous vein, anterior cutaneous vein of thigh.5. Just before piercing cribriform fascia-superficial epigastric, superficial circumflex iliac, superficial external pudendal.6. Just before termination-Deep external pudendal. {Reference: BDC. 6E vol2 pg125}