290 THE CIRCULATORY SYSTEM. 



foramen in the orbital plate of the frontal bone, then continues 

 distad to emerge from the orbit on the medial side of the eye ; 

 here it anastomoses with branches of the superficial temporal. 



6. A. palatina minor (Fig. 120, /). — The lesser palatine 

 artery leaves the internal maxillary distad of the carotid plexus, 

 near the caudal border of the maxillary bone. It passes 

 ventrocaudad into the soft palate. 



7. A. sphenopalatina. — The sphenopalatine is one of the 

 terminal branches of the internal maxillary; it passes mediad 

 through the sphenopalatine foramen into the nasal cavity, and 

 divides into numerous branches which supply the mucous 

 membrane of the nose. It gives off just before it enters the 

 sphenopalatine foramen the descending palatine (A. palatina 

 descendens), which passes into the posterior palatine canal and 

 emerges on the surface of the hard palate, where it ramifies. 



8. A. infraorbitalis (Fig. 120, o). — The infraorbital artery 

 is a direct continuation craniad of the internal maxillary. It 

 sends off numerous small branches to the teeth of the upper 

 jaw, and a rather large branch which passes to the lower eye- 

 lid. It then enters the infraorbital foramen, at the same time 

 dividing usually into two or three branches ; these emerge from 

 the foramen and supply the parts of the nose and upper lip 

 adjacent to the foramen (Fig. 131, r). 



A. suBCLAViA. The Subclavian Artery. 



The left subclavian (Fig. 118, c) arises from the convexity 

 of the aortic arch just distad of the origin of the innominate 

 artery, and about two or three centimeters from the heart. It 

 passes craniad and slightly to the left, and turns into the left 

 arm just craniad of the first rib. 



The right subclavian (Fig. 1 15, w) is a direct continuation 

 of the innominate, the artery receiving the name subclavian 

 after the right common carotid is given off, usually at about the 

 level of the second or third intercostal space. 



The subclavian has the following branches: the vertebral 

 artery (Fig. 118,^'), the internal mammary (Fig. 118, h), 

 the costocervical axis (Fig. 118, g), the thyrocervical axis 

 (Fig. ii8,y). Beyond the last-named branch it continues into 

 the arm as the axillary artery (Fig. 118, /; Fig. 122, g). 



