THE ARTERIES. . 449 



the opposite side, in a groove along the ventral 

 surface of the vertebral column. 



About half an inch from its origin it gives 

 off the vertebral artery, which runs forwards 

 along the side of the neck, in the vertebrar- 

 terial canal of the cervical vertebrae. 



Opposite the angle of the jaw, the carotid 

 artery divides into external and internal 

 carotid arteries. 



a. The external carotid artery supplies the tongue, 

 the muscles of the jaws, and other parts 

 of the head. 



ft. The internal carotid artery enters the skull 

 by a foramen in its base, and supplies the 

 brain. 



ii. The subclavian artery, which is much the larger 

 of the two branches of the innominate, runs 

 outwards, and divides, after a course of not 

 more than an eighth of an inch, into the 

 brachial and pectoral arteries. 



a. The brachial artery runs straight outwards to 

 the wing, giving a branch to the shoulder- 

 joint. 



/?. The pectoral artery is a large vessel, very- 

 little smaller than the innominate itself: 

 it runs outwards and backwards, looping 

 round the outer side of the sternal end of 

 the coraco'd, to enter the deeper surface 

 of the great pectoral muscle, in which it 

 divides into numerous branches. 



b. The right innominate artery has branches exactly 



corresponding to those of the left innominate. 



c. The dorsal aorta, which is rather smaller than 



either of the innominate arteries, arches over to 

 the right side, crosses the right pulmonary 

 artery, and then runs backwards along the 



