356 DISSECTION OF THE RABBIT. 



3. The pulmonary system consists of the pulmonary veins, 

 which have already been described (p. 351). 



In drawing the veins make a large sketch of the head, neck, 

 ribs, and abdomen. Then draw the veins in relation to them 

 and the chief organs. The portal vein had better be drawn 

 separately. 



C. The Arteries. 



The aTteries form two distinct systems, of which one, the 

 aortic system, conveys arterial blood from the left ventricle 

 to all parts of the body ; while the other, or pulmonary 

 system, carries venous blood from the right ventricle to the 

 lungs. The arteries are thicker-walled, and hence paler in 

 colour, than the veins. 



The aortic system should be dissected first. Clean the 

 aorta along its whole length, and follow the arteries arising 

 from it to their distribution. 



During the dissection of the arteries, take great care not to 

 damage or remove the nerves lying near them. 



1. The aorta arises from the base of the left ventricle, and, 



turning towards the left side to form the arch of 

 the aorta, runs backwards through the thorax and 

 abdomen. It lies on the ventral surface of the 

 vertebral column, and divides about an inch in 

 front of the level of the pubic symphysis into the 

 two" common iliac arteries. 



2. Arteries arising from the aorta in the thorax. 



a. The innominate artery arises from the commence- 

 ment of the arch of the aorta : it gives off, close 

 to its origin, the left carotid artery, and then 

 runs forwards a short distance and divides into 

 the right subclavian and right carotid arteries. 

 i. The right subclavian artery runs outwards just 

 in front of the first rib : it gives branches to 

 the shoulder, and runs on as the brachial artery 

 into the right fore-limb. Its principal branches 

 are the following : 



