214 THE HUMAN BODY. 



median nerve, 1, a branch of the brachial plexus which 

 supplies several muscles of the forearm and hand, the skin 

 over a great part of the palm, and the three inner fingers, 

 is seen alongside the artery. The larger veins of the part 

 are seen to form a more superficial network, joined here 

 and there, as for instance at *, by branches from deeper 

 'parts. Several small nerve-branches which supply the skin 

 (2, 3, 4) are seen among these veins. It is from the vessel, 

 cep, called the cephalic vein, just above the point where it 

 crosses the median nerve, that surgeons usually bleed a 

 patient. 



A great part of the blood of the^lower limb is brought 

 back by the long saplienous vein, which can be seen running 

 beneath the skin from the inner side of the ankle to the 

 top of the thigh. All the blood wfiich leaves the heart by 

 the aorta, except that flowing through the coronary arte- 

 ries, is finally collected into the superior and inferior venae 

 cavcB (cs and ci ? v Figs. 79 and 86^), and poured into the 

 right auricle. The 'jugular veiri$ which run down the 

 neck, carrying back the blood which went out along the 

 carotid arteries, unite below with tlie arm-vein (subclavian) 

 to form on each side an innominate vein (Asi and Ade, 

 Fig. 79) and the innominates unite to form the superior 

 cava. The coronary-artery blood after flowing through the 

 capillaries of the heart itself, also returns to this auricle by 

 the coronary veins. 



The Pulmonary Circulation. Through this the blood 

 gets back to the left side of the heart and so into the aorta 

 again. The pulmonary artery, dividing into branches for 

 each lung, ends- in the capillaries of those organs. From 

 these it is collected by the pulmonary veins which carry it 

 back to the left auricle, whence it passes to the left ventricle 

 to recommence its flow through the Body generally. 



The Course of the Blood. From what has been said it 

 is clear that the movement of the blood is a circulation. 

 Starting from any one chamber of the heart it will in time 

 return to it; but to do this it must pass through at least 

 two sets of capillaries; one of these is connected with the 

 aorta and the other with the pulmonary artery, and in its 



