210 THE HUMAN BODY. 



opposite the last lumbar vertebra by dividing into the right 

 and left common iliac arteries, which carry blood to the 

 lower limbs. We have then to consider the branches of the 

 arch of the aorta, and those of the descending aorta, which 

 latter is for convenience described by anatomists as consist- 

 ing of the thoracic aorta, extending from the end of the 

 arch to the diaphragm, and the abdominal aorta, extending 

 from the diaphragm to the final subdivision of the vessel. 



Branches of the Arch of the Aorta. From this arise 

 first the coronary arteries (crd and crs, Figs. 79 and 80) 

 which spring close to the heart, just above two of the 

 pouches of the semilunar valve, and carry blood into the 

 substance of that organ. The remaining branches of the 

 arch are three in number, and all arise from its convexity. 

 The first is the innominate artery (Ah, Fig. 79), which is 

 very short, immediately breaking up into the right subcla- 

 vian artery, and the right common carotid. Then comes 

 the left common carotid, Cs, and finally the left subclavian, 

 Ssi. 



Each subclavian artery runs out to the arm on its own 

 side and after giving off a vertebral artery (which runs up 

 the neck to the head in the vertebral canal of the transverse 

 processes of the cervical vertebrae), crosses the arm-pit and 

 takes there the name of the axillary artery. This con- 

 tinues down the arm as the brachial artery, which, giving 

 off branches on its way, runs to the front of the arm, and 

 just below the elbow-joint divides into the radial and. ulnar 

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

 Fig. 77.* These supply the forearm a nil end in the hand 

 by uniting 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 external 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, boing often seen 

 beating in thin persons on the side of the brow. The in- 



* P. 202. 



