Arteria subclavia. 201 



545. Course and Ramification of the Right Sub- 

 clavian Artery. 



The subclavian artery, Art. subclavia, arises on the right side 

 from the innominate artery, on the left from the arch of the aorta, passes 

 a short way up into the neck, arches outwards over the pleura and lung, 

 and rests between the anterior and middle scaleni muscles on the first 

 rib. At the outer border of the first rib it assumes the name of axillary 

 artery. Its five branches are the following : 



1. The vertebral artery, Art. vertebralis, enters the foramen 

 in the transverse process of the sixth cervical vertebra, and ascends 

 through the foramina in the transverse processes of all the vertebrae 

 above this. Above the upper border of the axis it inclines outwards and 

 upwards to the foramen in the transverse process of the atlas, through 

 which it passes; then it winds backwards and finally enters the skull 

 through the Foramen magnum. At the lower border of the Pons Varolii it 

 unites with the vessel of the opposite side to form the single basilar 

 artery. - - Up to its entrance into the cranium it gives off muscular 

 branches, spinal branches and the posterior meningeal 

 artery. After its entrance it gives off : the anterior and posterior 

 spinal, the two anterior of which unite to form a common trunk 5 then 

 the posterior inferior cerebellar to the posterior portion of the 

 cerebellum ; finally the anterior inferior cerebellar to the 

 anterior portion of the inferior cerebellar region. 



The basilar artery, Art. basilaris, formed by the junction of 

 the two vertebral arteries, extends from the posterior to the anterior border 

 of the Pons Varolii; where it divides into two branches, the right and 1 e f t 

 posterior cerebral or Art. profunda cerebri dextra et sinistra. 



