THE ANATOMY OF THE HEART AND BLOOD-VESSELS 333 



many places lie near or alongside the main artery of the 

 part, but there are many more large veins just beneath the skin 

 than there are large arteries. This is especially the case in the 

 limbs, the main veins of which are superficial, and can in many 

 persons be seen as faint blue marks through the skin. Fig. 106 

 represents the arm at the front of the elbow-joint after the skin 

 and subcutaneous areolar tissue and fat have been removed. The 

 brachial artery, B, colored red, is seen lying tolerably deep, and 

 accompanied by two small veins (vence comites) which communi- 

 cate by cross-branches. The great 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 saphenous vein, which can be seen in thin persons running 

 from the inner side of the ankle to the top of the thigh. All the 

 blood which leaves the heart by the aorta, except that flowing 

 through the coronary arteries, is finally collected into the superior 

 and inferior vence cavce (cs and a', Figs. 102 and 103), and poured 

 into the right auricle. The jugular veins which run down the neck, 

 carrying back the blood which went out along the carotid arteries, 

 unite below with the arm-vein (subclavian) to form on each side an 

 innominate vein (Asi and Ade, Fig. 102) and the innominates unite 

 to form the superior cava. The coronary-artery blood after flow- 

 ing through the capillaries of the heart itself also returns to this 

 auricle by the coronary veins and sinus. 



The Pulmonary Circulation (L, Fig. 99). 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 the 

 blood is collected by the pulmonary veins, which carry it back to 

 the left auricle, whence it passes to the left ventricle to recom- 

 mence its flow through the Body generally. 



