468 APPENDIX. 



way the nerves will be seen passing to the skin, while if the scalpel 

 were used the nerves might be cut.) 



Tie the axillary vein or its two branches in two places, and cut 

 the vein between the tied regions. Leave the arteries as guides for 

 dissection, bnt remove the veins. Now clean thoroughly the nerves 

 forming the brachial plexus as they pass from the thorax or neck. 

 Be careful not to injure any of the fine nerves or the interconnections 

 of the nerves in doing this. Find and distinguish clearly the fifth, 

 sixth, seventh, and eighth cervical nerves and the first thoracic, as 

 they emerge from the neck or thorax. (Compare Fig. 159 and Fig, 

 157, r-J7//and /'.) 



Follow out the branches of the plexus, noting the origin and 

 distribution of each branch, in order to determine its name. To 

 follow the phrenic (p. 388, and Fig. 157,/"), remove a portion of the 

 thoracic wall. In following the other branches of the plexus, pull 

 back the skin wherever an exposure is to be made, and separate the 

 muscles. The epitrochlearis may be cut near the elbow, and the 

 clavobrachial near the shoulder. In following the interosseous 

 branches of the median nerve the fifth head of the flexor profundus, 

 and the extensor brevis pollicis, may be cut. As a rule it will not 

 be necessary to cut other muscles. 



Thoracic and Lumbar Nerves. — One or two of the thoracic nerves 

 (p. 393) should be dissected from the outside by finding the inter- 

 costal nerve along the caudal border of one of the ribs and tracing it 

 in both directions. The nerve may be exposed by removing the 

 external muscles covering the rib, and cutting the external intercostal 

 muscles. The dorsal ramus should be traced after the ventral ramus 

 has been studied. 



The first lumbar nerve (p. 395) should be dissected in the same 

 way. 



The other lumbar and sacral nerves (pp. 395-400) are best dis- 

 sected from within. 



The alimentary canal and its appendages should be removed from 

 the abdomen, leaving only five or six centimeters of the caudal end 

 of the rectum. The kidneys and urogenital organs may be left, 

 to be removed during dissection. (Compare Fig. 162.) 



Turn one of the kidneys to the other side, and find the second 

 lumbar nerve (Fig. 162, a) appearing at the lateral border of the 

 iliopsoas muscle. Trace it to its origin; trace it also distad, follow- 

 ing both branches. It will be necessary to trace the nerves through 

 the abdominal wall, then find them from the outside, and follow 

 them to their distribution. 



The third nerve (Fig. 163, 3) may be found by dissecting apart 

 the fibre-bundles of the iliopsoas and psoas minor, and following in 

 the same way. The kidneys, ureters, vena cava, and aorta may be 

 removed as occasion arises. 



The remainder of the lumbar nerves may be found in order, in a 

 similar manner. Follow the saphenous nerve and its branches (p. 



