THE ANATOMY OF THE HEART AND BLOOD-VESSELS 331 



and ulnar arteries, the lower ends of which are seen at R and U in 

 Fig. 100. These supply the forearm and end in the hand by unit- 

 ing to form an arch, from which branches are given off to the 

 fingers. 



The common carotid arteries pass out of the chest into the neck, 

 along which they ascend on the sides of the windpipe. Opposite 

 the angle of the lower jaw each divides into an internal and exter- 

 nal carotid artery, right or left as the case may be. The external 

 ends mainly in branches for the face, scalp, and salivary glands, 

 one great subdivision of it with a tortuous course, the temporal 

 artery, being often seen in thin persons beating on the side of the 

 brow. The internal carotid artery enters the skull through an 

 aperture in its base and supplies the brain, which it will be re- 

 membered gets blood also through the vertebral arteries. 



Branches of the Thoracic Aorta. These are numerous but 

 small. Some, the intercostal arteries, run out between the ribs and 

 supply the chest-walls; others, the bronchial arteries, carry blood to 

 the lungs for their nourishment, that carried to them by the pul- 

 monary arteries being brought there for another purpose; and a few 

 other small branches are given to other neighboring parts. 



Branches of the Abdominal Aorta. These are both large and 

 numerous, supplying not only the wall of the posterior part of the 

 trunk, but the important organs in the abdominal cavity. The 

 larger are : the celiac axis which supplies stomach, spleen, liver, and 

 pancreas; the 'Superior mesenteric artery, which supplies a great part 

 of the intestine; the^renal arteries, one for each kidney; and finally 

 the inferior mesenteric artery, which supplies the rest of the in- 

 testine. Besides these the abdominal aorta gives off very many 

 smaller branches. 



Arteries of the Lower Limbs. Each common iliac divides into 

 an internal and external iliac artery. The former ends mainly in 

 branches to parts lying in the pelvis, but the latter passes into the 

 thighs and there takes the name of the femoral artery. At first this 

 lies on the ventral aspect of the limb, but lower down passes to the 

 ba?k of the femur, and above the knee-joinfc (where it is called the 

 popliteal artery] divides into the anterior and posterior tibial ar- 

 teries, which supply the leg and foot. 



The Capillaries. As the arteries are followed from the heart, 

 their branches become smaller and smaller, and finally cannot be 



