510 APPENDIX 



THE CIRCULATORY SYSTEM 



A good introduction to the study of the circulation is the dis- 

 section of the chief arteries and veins of the cat. 



Preparation. Inject the arterial system with a starch mass 

 colored red. To do this expose the heart and tie the nozzle of the 

 injecting syringe directly into the tip of the left ventricle. The 

 injection drives the blood into the veins so that they retain their 

 natural blue color. Trace the vessels by tearing cautiously with 

 the handle of a scalpel or some blunt instrument. Do not cut un- 

 less directions are given. Lay the thorax and abdomen wide open 

 by a median incision. 



Heart. The process of injection mutilates the heart. A separate 

 exercise on the sheep's heart is described below. 



ARTERIES OF THE THORAX 



The Aorta. This is a single great artery arising from the left 

 chamber of the heart. It curves sharply to the left, thus making 

 the arch of the aorta. 



Coronary Artery. Two in number arising within the heart; they 

 are small and the first branches seen. They supply the heart. 



Innominate. This arises from the convexity of the arch very 

 near its origin; it gives rise to the right and left carotid arteries. 



Subclavians. The right subclavian is a continuation of the in- 

 nominate; the left subclavian, the next large branch of the aorta, is 

 given off close to the innominate. 



Intercostal Arteries. These are seen, one below each pair of ribs. 



ARTERIES OF THE ABDOMEN 



Abdominal Aorta. This is a continuation of the thoracic aorta. 

 Turn the stomach and intestines to the right, press upon the median 

 line against the spinal column, and the injected aorta will be felt. 

 Tear away the peritoneum and follow the vessel from the dia- 

 phragm and note branches. 



Celiac Axis. As the aorta enters the abdomen there is given 

 off a large branch, the celiac axis. This divides into three 

 branches, the first being the gastric, which goes to the stomach. 

 The second goes to the liver and is called the hepatic artery. Turn 



