ANGIOLOGY 209 



arteries, which are given off from the common aorta just above the 

 semi-lunar valves. 



A right, or anterior, and a left, or posterior, coronary from their 

 point of origin, turn in a ventral direction between the root of the 

 aorta and the pulmonary artery, the right going to the right coronary 

 groove and the left to the left coronary groove in the crown furrow. 

 From here they send branches into the heart. The anterior, right, 

 coronary, or coronaria dextra, the larger, is given off from the 

 inferior wall of the aorta. It divides into a ramus superficiaUs 

 and a ramus profundus. The ramus superficiaUs enters the crown 

 furrow and divides into two or three branches on the right heart 

 waU. These branches extend to the apex of the heart. Twigs from 

 this artery along its course extend into the muscular wall reaching 

 the posterior of the coronary groove where they anastomose with 

 those of the left coronary, the ramus profundus, and with other 

 branches from the s£tme artery. The ramus profundus, larger than 

 the preceding, gives off fine branches into the walls of the aorta and 

 of the pulmonary artery, then enters from behind into the right wall 

 of the septum ventriculorum, extends into the apex of the heart, and 

 suppUes the septum, or right inner chamber wall with the last branch, 

 this breaking through the posterior wall of the auricular appendage. 



The posterior, left coronary, or coronaria sinistra, originates from 

 the dorsal wall of the aorta, proceeds as one branch on the upper 

 surface of the left auricular appendix, and then extends between the 

 left appendix and the pulmonary artery to the ventral surface of the 

 heart. On the left side it supplies the wall of the pulmonary artery 

 and gives off a ramus profundus. It sometimes divides into two 

 parts and supplies the ventral wall of the right chamber and then 

 extends to the left wall of the septum medium. The rest of the 

 coronaria sinistra enters into the left crown furrow as the ramus 

 superficiaUs, which provides the left and dorsal upper surface of 

 the left chamber to the apex. From this furrow it extends into the 

 left chamber and the left appendage, and finally fuses with the 

 ramus superficiaUs of the coronaria dextra. 



THE BLOOD-VESSELS 



The blood-vessels consist of arteries, veins and capillaries. 

 The Structure of the Capillaries and Arteries. — The capillaries 

 are minute vessels which connect the arterioles, or terminal arteries, 



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