8o OUTLINES OF ANATOMY. 



Descending Portion of the Arch Relations: 

 Right side. 

 Left side. 

 Variations in the arch of the aorta : 



Variations in the aortic arch itself : 



(a) Variations depending on abnormalities in development of the ventral 



aortic stem. 

 (])) Variations depending on abnormalities in development of the fourth 



and fifth aortic or branchial arches. 

 (V) Variations depending on abnormalities in development of the dorsal 



aortic stems. 



Branches of the arch of the aorta : 

 Ascending portion. 

 Transverse portion. 

 Descending portion. 

 Transverse portion, II, 503. (495) 

 Innominate. 

 Left common carotid. 

 Left subclavian artery. 



Innominate, or brachio-cephalic artery, 503-4. (495-6) 

 Relations : In front. 

 Behind. 

 Right side. 

 Left side. 



Variations in the innominate artery. 



Branches of the innominate artery : 



(1) Right common carotid. 



(2) Right subclavian. 



Thoracic portion of the left common carotid, 505-6. (497) 

 Relations : In front. 



Behind. 



Right side. 



Left side. 



Left subclavian artery, 536-7. (527-8) 

 Relations : In front. 



Behind. 



Right side. 



Left side. 



The chief variations in the three primary branches of the transverse por- 

 tions of the aortic arch, 501. (493) 



(7), (2}, (J), (*), (J), (6\ ' 



Strip the pleura from the anterior and posterior surfaces of the root of the lung. Trace the pulmonary 

 artery and its divisions to the lung, and the pulmonary veins from the lung to the left auricle. Dissect 

 out the areolar tissue, glands, etc., and expose and separate the component parts of the root of the 

 lung. Special care should be exercised not to injure the nerve plexuses and the branches to and from 

 them. The anterior pulmonary plexus consists of a few small fibres in front of the root of the lung ; the 

 posterior plexus is larger and readily exposed. The pneumogastric nerves should be exposed on each 

 side and traced to the posterior plexus. To expose the pneumogastric nerve and the posterior plexus on 

 each side, draw the lung forward and over to the opposite side and retain it in place with hooks while 

 exposing the structures behind the root. 



Anterior pulmonary branches (plexus), 819. (800) 

 Pulmonary artery, conus arteriosus, 491-2-3-5. (483-4-5-7) 

 Trunk of the pulmonary artery : 



Ductus arteriosus, or ductus Botalli. 

 Relations : In front. 

 Behind. 

 Right. 

 Left. 



