WESLEY D. ANDERSON 
777 
Figure 11. — Sternocostal surface of human thoracic 
viscera in situ. 
Reproduced by permission from: W. Henry Hollinshead, TEXT- 
BOOK OF ANATOMY (ed. 2). Copyright (1967). Hoeber Medical 
Division — Harper & Row., New York. 
ganglion. The vertebral nerve arises from the 
cervicothoracic ganglion and dips beneath the 
brachial plexus to enter the transverse foramen 
with the vertebral artery. Other small nerves 
pass directly from the cervicothoracic ganglion 
to the lateral surface of the trachea and course 
beneath the costocervical trunk to unite as a 
small ganglion on the dorsolateral surface of the 
trachea, termed the middle cervical ganglion 
(Figures 12 and 13). In the sheep and some 
other ruminants, the sympathetic trunk joins 
the vagus in the cervical region and is continued 
as the vagosympathetic trunk. 
Coronary Arteries and Cardiac Veins 
In man and other mammals the right and 
left coronary arteries are named for their ori- 
gins from the right and left aortic sinuses and 
their course and termination on their respective 
surfaces of the heart. 
The left coronary artery, which supplies the 
majority of the heart in ruminants and dog, 
emerges from behind the left side of the pul- 
monary trunk and bifurcates into a descending 
branch, the cranial interventricular artery and 
a circumflex branch. After arising from the 
ascending aorta at the left aortic sinus, the 
left coronary artery in the dog often gives ori- 
gin to a septal branch to the interventricular 
septum. The septal artery when it arises at this 
position presents a technical problem when one 
is desirous of placing an electromagnetic blood 
flow probe around the trunk of the left coronary 
for direct and continuous blood flow measure- 
ments (Figure 14). The cranial interventricular 
artery in quadrupeds descends in its sulcus 
with the great cardiac vein to the apex of the 
heart where it often enters into anastomoses 
with the caudal interventricular artery de- 
scending from the caudal (posterior) surface 
of the heart. The circumflex branch courses to 
the left in the coronary sulcus with the great 
cardiac vein and gives origin to the left mar- 
ginal and caudal ventricular arteries. In rumi- 
nants and the dog, the left coronary artery 
terminates on the caudal surface of the heart 
as the caudal interventricular artery (Figure 
15) while the left coronary artery in man most 
commonly ends on the posterior (diaphrag- 
matic) surface of the heart as the left ventric- 
ular artery. Thus the majority of the front as 
well as the back surface of the ruminant and 
dog heart is supplied by the left coronary artery 
(Figure 15), while the majority of the posterior 
surface of the human heart is usually supplied 
by the right coronary artery. The left coronary 
artery of the dog is larger and supplies a 
greater amount of total myocardium than the 
right coronary artery. In dogs weighing 13-18 
kg an electromagnetic blood flow transducer 
with a luminal diameter of 2.5-3 mm will us- 
ually be satisfactory in obtaining blood flow 
measurements from the left coronary artery. 
The cranial interventricular branch of the left 
coronary in the dog is approximately the same 
diameter as the circumflex branch and is ap- 
proximately seven cm long. It has many tiny 
ventricular branches in addition to a larger left 
ventricular artery at the apex of the heart and 
is similar in this respect to man (Figure 16). 
