The _subclavian_ is the artery of the upper extremity but its vertebral branch goes to the brain, where with its fellow it forms the _basilar artery_, whose branches together with the branches of the internal carotid form the _circle of Willis_ at the base of the brain. Other branches of the subclavian are the _thyroid axis_, with branches to the neck and shoulders; the _internal mammary_, with branches to the chest walls, mediastinum, and diaphragm, such as the musculo-phrenic and superior epigastric; and the _superior intercostal_. At the lower border of the first rib, over which it passes, the name _axillary_ is substituted for _subclavian_, while at the lower border of the axilla, where it starts down the arm, it is called the _brachial artery_. At the elbow the brachial divides into the _radial_ and _ulnar arteries_. The _axillary 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_.