414 DISSECTION OF THE PIGEON 



a. The left innominate artery is a short wide artery, 

 which divides, after a course of about a quarter of 

 an inch, into two vessels of very unequal size. 



i. The left carotid artery, which is much the 

 smaller of the two, runs forwards along the 

 neck, lying close to its fellow of 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. 

 /3. The internal carotid artery enters the skull 



by a foramen at 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. 



/3. 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 coracoid, to enter the deeper surface 

 of the great pectoral muscle, in which it 

 divides into numerous branches. 



