This document discusses the venous drainage system of the lower extremities. It describes the three types of veins - deep, superficial, and perforating veins. It provides details on the long and short saphenous veins and deep veins like the femoral vein. Perforating veins that connect superficial and deep veins are also explained. Diagnosis of venous insufficiency involves physical exam, Doppler ultrasound, duplex ultrasound, and other tests. Management options for varicose veins and venous insufficiency include compression stockings, surgery like ligation and stripping, and minimally invasive procedures like sclerotherapy, radiofrequency ablation, and endovenous laser treatment.