artery sends branches to the chest and shoulder and is more frequently injured than any other artery except the popliteal. Aneurism may occur in it and is very likely to occur in the thoracic aorta.
From the thoracic aorta branches go to various of the chest contents, while the abdominal aorta supplies the abdominal viscera. Among the branches of the abdominal aorta are: the celiac axis, which has a gastric, an hepatic, and a splenic branch; the superior and inferior mesenteric to the intestines; the renal; the suprarenal; the spermatic or ovarian; the inferior phrenic; and the lumbar.
The common iliacs divide at the upper edge of the sacrum into the external and internal iliacs, of which the latter with its branches supplies the walls and viscera of the pelvis and the inner part of the thigh. The external iliac and its branches go to the thigh, leg, and foot.
Veins.—Of the veins few need be mentioned by name. The deep veins have the same names as the arteries they accompany, though there are two innominate veins where there is only one innominate artery, the subclavian and internal jugular veins on either side joining to form an innominate vein and the two innominates in turn forming the superior vena cava. Of the superficial veins the external and internal jugular correspond to the common carotid arteries and return the blood from the head and face. The external jugular vein is important because it is the largest superficial vein in the neck and is often cut in suicide. The median vein is found at the bend of the elbow and is used in letting blood and in giving salt solution, while the basilic is on the inner side and the median cephalic on the outer side of the upper arm. Varicosity often occurs in the internal or long saphenous and the external or short saphenous in the leg. The inferior vena cava is formed by the juncture of the two common iliac veins.
Portal Circulation.—The portal system of veins includes four large trunks which collect the blood from the viscera
