The document summarizes the anatomy and physiology of the veins in the lower limbs. It describes how blood flows from the superficial to deep veins through perforating veins, aided by valves that prevent backflow. It explains that incompetence of these valves can cause varicose veins due to increased pressure in the superficial veins. It also briefly discusses soft tissue changes that can occur with longstanding varicose veins like pigmentation and ulceration.