312 A Composite Study of the Subclavian Artery in Man 



Part 111 in 1% of them, dividing almost immediately into the superior 

 intercostal and the deep cervical arteries. The origin from Parts II and 

 III is on the right side of the body in all cases. 



The supenor intercostal artery '" arises on the right side of the body 

 from the costo-cervical trunk in 41% of the subjects; from Part II in 

 10% of the subjects, and from Part I in 3% of them. It arises on the 

 left side of the body from the costo-cervical trunk in 38% of the sub- 

 jects, and from Part I in 8% of them. 



The deep cervical artery "^ arises from the costo-cervical trunk in 83% 

 of the subjects; from the subclavian artery in 13% of them, and from 

 the inferior thyroid in 4% of them. It passes above the first rib in 

 82%. of the subjects, and below it in 18% of them. The distribution 

 of the deep cervical artery varies in inverse proportion to that of the 

 ascending cervical and the superior intercostal arteries. 



SECTioisr C. — Discussion. 



First. — We have demonstrated that the branches are arranged in a 

 different manner on the two sides of the body. Fig. 7 shows this. 



This figure represents the most usual arrangement of the branches 

 of the subclavian artery as found on each side of the body, the difference 

 between the two sides of the body being chiefly in the origin of the trans- 

 verse cervical artery." The type shown on the right side of the body 

 occurred in 51% of all the cases classified on that side. The type shown 

 on the left side of the body occurred in 55% of all the cases classified 

 on that side. The distribution of the anterior branches is put on the 

 right side of the body, and that of the posterior branches on the left side 

 of the body in this figure. 



Second. — The number of branches arising from Part II on the right 

 side is more than double those from the same part on the left side, count- 

 ing all cases. This is due to the origin of the transverse cervical artery 

 and occasionally (11 times) the superior intercostal artery from Part 

 II on the right side." 



Third. — The relation of the branches to age discloses the apparent 

 abnormality of infantile subclavian arteries. There are 23 infant sub- 

 jects worked out, 17 male negro, 4 female negro, and 2 male white. No 

 two subjects show the same arrangement, all being irregular. 



" Table 10, p. 320. 



"Table 11, p. 320. 



^= Tables 12, 13, 14, 15, and 16, pp. 320, 321, 322, and 323. 



"Tables 5. 10, 13, and 14, pp. 319, 320, and 321. 



