BRANCHES OF THE ASCENDING AORTA. 755 
Visceral. ‘ Parietal. 
Unpaired. Paired. Unpaired. Paired. 
Coeliac axis Suprarenal Middle sacral Inferior phrenic | 
Superior mesen- Renal Lumbar (four pairs) 
| teric Spermatic or Common iliac | 
Inferior mesen- ovarian | 
teric | 
BRANCHES OF THE ASCENDING AORTA. 
CoRONARY ARTERIES. 
The coronary arteries are two in number, a right anda left; they are distributed 
almost entirely to the heart, but give also some small branches to the roots of the 
great vessels, and to the pericardium (Figs. 545, 546, and 549). 
The right coronary artery (a. coronaria dextra) springs from the anterior 
sinus of Valsalva. It runs forwards, between the root of the pulmonary artery 
and the right auricular appendix, to the auriculo-ventricular sulcus, in which it 
passes to the right,and then, turning round the margin of the heart, is continued to 
the left as far as the posterior end of the inferior interventricular sulcus, where it 
ends by dividing into two terminal branches. It is accompanied by branches 
from the cardiac plexus, and is in relation with the right coronary vein. 
Branches.—Of the two terminal branches, one, the transverse (ramus circumflexus), is of 
small size ; it is simply the continuation of the main trunk which runs farther to the left to 
anastomose with the transverse branch of the left coronary artery. The other, the interventricular 
(ramus descendens), is much larger than the transverse branch. It runs forwards in the inferior 
interventricular sulcus, supplies both ventricles, and anastomoses, at the apex of the heart, with 
the interventricular branch of the left coronary artery. 
In addition to the terminal branches small aortic and pulmonary twigs are distributed to the 
roots of the aorta and pulmonary artery respectively. A right auricular branch passes upwards 
on the anterior surface of the right auricle, between it and the ascending aorta; one or more 
preventricular branches, of small size, descend on the anterior surface of the right ventricle ; a 
branch of larger size, the marginal artery, descends along the right margin and gives branches to 
both surfaces of the right ventricle. 
The left coronary artery (a. coronaria sinistra) arises from the left posterior 
sinus of Valsalva. In its course and distribution it resembles in many respects 
the right coronary artery, the chief difference being that it divides much sooner 
into its two terminal branches; the trunk of the artery is therefore correspondingly 
short. From its origin it runs forwards between the root of the pulmonary artery 
and the left auricular appendix, and, reaching the auriculo-ventricular sulcus at the 
upper end of the anterior interventricular groove, divides immediately into trans- 
verse and interventricular terminal branches. 
Branches.—The transverse terminal branch (ramus circumflexus) runs to the left margin of 
the heart, and there turns to the inferior surface where it comes into relation with the coronary 
sinus; it ends by anastomosing with the transverse branch of the right coronary artery. It 
supplies the left auricle, the lett margin of the heart, and the posterior part of the lower surface 
of the left ventricle. The interventricular terminal branch (ramus descendens anterior) passes 
down the anterior interventricular suleus to the apex of the heart, where it anastomoses with 
the interventricular branch from the right coronary ; it supplies both ventricles, and is accom- 
panied by cardiac nerves and by the great cardiac vein. 
A left auricular branch, or branches of small size, pass to the wall of the left auricle, and small 
aortic and pulmonary branches are also given to the roots of the aorta and pulmonary artery. 
BRANCHES OF THE ARCH OF THE AORTA. 
The branches which arise from the arch of the aorta supply the head and neck, 
the upper extremities, and part of the body wall. i 
They are three in number, viz. the innominate, the left common carotid, and 
