The document describes several veins in the leg that drain blood from various areas and converge to form larger veins. The metatarsal veins unite to form the post tibial vein, which drains the area near the back of the tibia. The popliteal vein receives blood from the fusion of the fibular, anterior tibial, and posterior tibial veins and drains the back of the knee. The femoral vein receives blood from the great saphenous vein, deep femoral vein, and femoral circumflex vein and drains the head and neck of the femur.