ANGIOLOGY 



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do not take their origin from the aorta in numerous and regular 

 branches as in mammals; they consist originally of but few vessels, 

 which are multiplied by anastomoses with each other and with 

 the arteries which come out of the spinal canal. An arterial plexus 

 is thus formed around the head of each rib, from which a vessel 

 is sent to each of the intercostal muscles and ribs and are continued 



Fig. 63.— The vascular system injected, i, The heart. 2, The posterior 

 aorta. 3, The right brachiocephalic artery. 4, The left brachiocephalic artery. 

 5, The anterior mesenteric artery showing its many branches and anastomoses 

 near and on the intestines. It is accompanied by branches of the mesenteric 

 vein. 6, The rectal branch of the posterior mesenteric artery. 7, The duodenal, 

 loop and pancreas showing the pancreatic artery. 8, The anus. 9, The cloaca. 

 10, The liver. 11, The lungs. 12, The right subclavian artery. 13, The right 

 carotid artery. 14, The right anterior, vena cava. 15, The subclavian vein. 

 16. The right jugular vein. 17, The carotid trunk. 18, The posterior vena cava. 



into the muscles upon the outside of the body and its integuments. 

 The anastomosis of the intercostal arteries round the ribs is similar 

 to the plexus, which is produced by the great sympathetic nerve in 

 the same location. The lumbar arteries are given off farther pos- 

 teriorly and along the lumbar region. The lumbar, like the dorsal 

 branches are given off in pairs. These arterial branches pass along 

 the thigh and the upper sacral vertebral region, and supply those 

 parts. VentraUy they are covered by the kidneys and pass into 



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