About two-thirds of the way to the knee the artery takes the name _popliteal_. It lies superficially in the popliteal space back of the knee, but above and below it is covered with muscles. Its branches supply the knee-joint and nearby muscles and are unimportant. At the lower border of the _popliteus muscle_, a small muscle at the knee, it divides into the _anterior and posterior tibial arteries_. The course of the former of these may be marked by a line from the inner side of the head of the fibula to midway between the malleoli at the front of the ankle, where it terminates in the _dorsalis pedis artery_ for the back of the foot. By this last the pulse is sometimes taken and its pulsation is a guide in determining how high up to amputate in gangrene of the foot. The posterior tibial extends obliquely down the back of the leg to the heel, where it divides into the _internal and external plantar arteries_ which go to the sole of the foot. Its most important branch is the _peroneal_. Besides the _deep veins_ accompanying the arteries there are the _superficial veins_, the _internal_ or _long saphenous_ on the inner side of the leg and thigh and the _external_ or _short saphenous_ on the middle of the leg posteriorly and emptying into the popliteal vein. Varicosity often occurs in these veins. =Nerves.=--The nerves of the muscles about the hip are branches of the _lumbar nerve_. The _anterior crural_ supplies the anterior part of the thigh, the _gluteal_ the muscles of the same name, and the _great sciatic_ the large muscles of the back of the thigh. Below the knee the _anterior tibial_ goes to the tibialis anticus and the _internal popliteal_ to the muscles of the calf, while the peroneus muscles are supplied by the _musculo-cutaneous_. INDEX.