Varicose Veins
Varicose veins develop in the superficial veins of the leg and mainly affect the long saphenous vein although it is not uncommon for the short saphenous vein to be involved and indeed other major tributaries nearly always are if these two vessels are affected.

Varicose veins are higgledy-piggledy, dilated veins whose valves have failed allowing increasing amounts of blood to reflux the wrong way down the limb.

(A) As the vein dilates the wall stretches in both width and length so that the vein becomes tortuous.

(B) As the situation gets worse the veins become so dilated that large sacs form at the bends.

(C) Turbulent flow occurs with areas of stagnation like extreme bends

(D) in an otherwise fast running river and the vein can sometimes thrombose leading to inflammation called superficial thrombophlebitis (which is a fancy Latin way of saying "inflamed vein").