DISSECTION OF THE VASCULAR SYSTEM. 59 



12. The Internal Maxillary Artery. Just beyond the 

 orifrin of the facial the external carotid divides into 

 two branches, the larger being the internal maxillary, 

 distributed to the inner side of the mandible, maxilla, 

 etc.; the smaller branch is 



13. The Temporal Artery, distributed to the mus- 

 cles and integument of the side of the head. 



14. The Right Sub-clavian Artery. Beyond the ori- 

 gin of the two common carotids the brachio-cephalic 

 artery is known as the right sub-clavian artery. The 

 chief branches are as follows : 



15. The Vertebral Artery, a branch which passes 

 dorsally to reach the vertebral canal of the spinal 

 column, through which it reaches the interior of the 

 skull to supply the brain. 



16. The Superior Intercostal Artery comes off quite 

 close to the vertebral, sometimes forming a branch of 

 it. It is distributed to the three anterior ribs. 



17. The Sternal {intcnial mainuiary>) Artery, given 

 off a little beyond the last. In company with the 

 artery of the other side it passes along the under sur- 

 face of the sternum, supplying it and the adjacent por- 

 tions of the ribs. 



18. The Thyroid Axis arises usually somewhat 

 nearer the heart than the last, but from the anterior 

 border of the sub-clavian. It seems to be homologous 

 with the thyroid axis of human anatomy, but has a 

 different distribution. It divides into branches which 

 supply the muscles of the root of the neck and of 

 the supra-scapular region. 



19. The Pectoral Branches. Beyond the thyroid 

 axis the sub-clavian artery, now known as the axillary, 

 gives off one or two branches which are distributed 

 chiefly to the pectoral muscle. 



