VEINS, LYMPHATICS, ARTERIES, AND NERVES 7 1 



waste products away from the cells and carbohydrate and 

 protein foods from the digestive tract to the liver, thence to the 

 arterial system. Unfortunately, the injection of veins meets 

 with mechanical difhculties, in the form of valves, which mark- 

 edly inhibit studying these vessels. The general plan and 

 course of the systemic and pulmonary veins is essentially 

 the same as that of the arteries. Some of striking exceptions 

 to the rule that veins and arteries usually take parallel courses 

 and the same name are the azygos (p. loi), cephalic (p. 73), 

 small saphenous (p. 82), and hepatic portal (p. 107, Fig. 30) 

 veins. Veins anastomose more freely than do arteries. The 

 student will get much more information out of his dissections 

 if he will remember an earlier admonition that the arteries, 

 veins, and lymphatics constitute the essential transportation 

 system of the body and as such they convey nutrient materials 

 to each muscle, bone, or other organ or structure in the body 

 and waste materials away from each and all of them, and that 

 the nerves and their specialized structures constitute a system 

 of communication by means of which the various activities of 

 muscles, vessels, other structures, and organs in general are 

 directed and coordinated. 



There are two important cautions to bear in mind in dissect- 

 ing the axillary region: (i) In transecting the sternal ends of the 

 pectoral muscles do not accidentally cut the axillary vessels or 

 the branchial plexus. (2) In dissecting the axillary region, and 

 at all subsequent times, be careful not to break the axial artery 

 or axial vein. After the pectoral muscles have been transected, 

 these vessels and the nerves are exposed to any strain which 

 may be exerted on the superior Hmb. To prepare for the first 

 incision lay the rabbit on its back with its right side toward the 

 operator and support it in this position by placing the fingers 

 of the left hand on its shoulder and neck region in such way that 

 the pectoral muscles are exposed. The contour of the latero- 

 ventral skeletal structure of the thorax must be recalled so 

 that the student will know exactly where the knife must pass 



