576 



THE ARTERIES. 



THE SUBCLAVIAN ARTERIES (Fig. 359). 



The subclavian artery on the right side arises from the innominate artery 

 opposite the right sterno-clavicular articulation ; on the left side it arises from the 

 arch of the aorta. It follows, therefore, that these two vessels must, in the first 

 part of their course, differ in their length, their direction, and their relation with 

 neighboring parts. 



In order to facilitate the description of these vessels, more especially from a 



Phrenic nerve. 

 I Vertebral artery. 



I 



Inferior thyroid artery. 



Supra-scapular artery 



I 



Supra-scapular nerve. 

 I 



i 



Pneumogastric 

 nerve. 



^Int. mammary artery. 



Innominate vein. 

 nominate artery. 



Musculo-cutaneous j 

 nerve. 



\-\Profunda artery. 



FIG. 359. The subclavian artery, showing its relations. (From a preparation in the Museum of the Royal 

 College of Surgeons.) 



surgical point of view, each subclavian artery has been divided into three parts. 

 The first portion, on the right side, passes upward and outward from the origin 

 of the vessel to the inner border of the Scalenus anticus. On the left side it ascends 

 nearly vertically, to gain the inner border of that muscle. The second part passes 

 outward, behind the Scalenus anticus ; and the third part passes from the outer 

 margin of that muscle, beneath the clavicle, to the lower border of the first rib, 

 where it becomes the axillary artery. The first portion of these two vessels 

 differs so much in its course and in its relation with neighboring parts that it 

 will be described separately. The second and third parts are alike on the two 

 sides. 



