Venous System

and intestines. The aorta later divides into the left and right common iliacs, which supply the lower extremities (fig. 1-35). ARTERIES OF THE LOWER EXTREM- ITIES.—The left and right common iliacs, upon entering the thigh, become the femoral artery. At the knee, this same vessel is named the popliteal artery (fig. 1-35). Venous System Venous circulation is responsible for returning the blood to the heart after exchanges of gases, nutrients, and wastes have occurred between the blood and body cells (fig. 1-36). To return this blood to the heart for reoxygenation, the venous system begins with the merging of capillaries into venules, venules into small veins, and small veins into larger veins. The blood vessel paths of the venous system are difficult to 1-29 HM3F0135C LEFT COMMON CAROTID LEFT SUBCLAVIAN PULMONARY AXILLARY BRACHIAL LEFT CORONARY RADIAL ULNAR INTERNAL CAROTID EXTERNAL CAROTID RIGHT COMMON CAROTID RIGHT SUBCLAVIAN INNOMINATE ARCH OF AORTA RIGHT CORONARY AORTA COMMON ILIAC EXTERNAL ILIAC FEMORAL POPLITEAL Figure 1-35.—Principal vessels of the arterial system.