skin of the face and the internal supplying the brain and the eyes.
The subclavian arteries are so named because they run underneath the clavicle. They supply the upper extremity, branching off to the back, chest, neck, and brain through the spinal column (fig. 3-31).
The large artery going to the arm is called the axillary. It divides into the ulnar and radial arteries. The radial artery is the one at the wrist that you feel to take the pulse of your patient. It is located on the thumb side (fig. 3-32).
Figure 3-32.Arteries and veins of the upper extremity.
In the abdomen the aorta gives off branches to the abdominal viscera, including the stomach, liver, spleen, kidneys, and intestines. It finally divides into the left and right common iliacs, which supply the lower extremities. On entering the thigh, this artery is called the femoral artery.
At the knee it becomes the popliteal artery (fig. 3-33). At the end of the arterioles is a system of minute vessels that vary in structure, but which are spoken of collectively as CAPILLARIES. It is from these capillaries that the tissues of the body are fed. There are approximately 60,000 miles of capillaries in the body. As the blood passes through the capillaries, it releases oxygen and nutritive substances to the tissues and takes up various waste products to be carried away by the veins.
Figure 3-33.Arteries and veins of the lower extremity.
VEINS comprise a system of vessels that collect blood from the capillaries and carry it back to the heart. Veins begin as tiny venules formed from the capillaries. Joining together as tiny rivulets, they connect and form a small stream. The force of muscles contracting adjacent to veins aids in the forward propulsion of blood on its return to the heart. Valves, spaced frequently along the larger veins, prevent the backflow of blood.
Since arterial blood arises at the heart, we trace arteries from the heart. To return blood to the heart, we trace veins from the small venules back through larger veins. There are three principal