the knee the popliteal artery runs through the popliteal fossa to the popliteal muscle where it divides into anterior and posterior tibial arteries. In the lower leg, the anterior tibial enters the extensor compartment near the upper border of the interosseus membrane to descend between the tibialis anterior and the extensor hallucis longus. Distal to the superior and extensor retinacula of the foot it becomes the dorsal artery of the foot. The posterior tibial forms a direct continuation of the popliteal artery which enters the flexor compartment of the lower leg to descend behind the medial malleolus where it divides into the medial and lateral plantar arteries, of which the posterior branch gives rise to the fibular artery. For practical reasons the lower limb is subdivided into somewhat arbitrary regions: The regions of the hip are all located in the thigh: anteriorly, the subinguinal region is bounded by the inguinal ligament, the sartorius, and the pectineus and forms part of the femoral triangle which extends distally to the adductor longus. Posteriorly, the gluteal region corresponds to the gluteus maximus. The anterior region of the thigh extends distally from the femoral triangle to the region of the knee and laterally to the tensor fasciae latae. The posterior region ends distally before the popliteal fossa. The anterior and posterior regions of the knee extend from the proximal regions down to the level of the tuberosity of the tibia. In the lower leg the anterior and posterior regions extend down to the malleoli. Behind the malleoli are the lateral and medial retromalleolar regions and behind these is the region of the heel. Finally, the foot is subdivided into a dorsal region superiorly and a plantar region inferiorly. Veins The veins are subdivided into three systems. The deep veins return approximately 85 percent of the blood and the superficial veins approximately 15 percent. A series of perforator veins interconnect the superficial and deep systems. In the standing posture, the veins of the leg have to handle an exceptional load as they act against gravity when they return the blood to the heart. The venous valves assist in maintaining the superficial to deep direction of the blood flow. Superficial veins: Great saphenous vein Small saphenous Deep veins: Femoral vein, whose segment is the common femoral vein Popliteal vein Anterior tibial vein Posterior tibial vein Fibular vein Nerve supply The sensory and motor innervation to the