THE TEETH. 227 



submental, pterygoid and masseteric, inferior labial, infe- 

 rior coronary, superior coronary, later alis nasi, and angular. 

 Of these branches, the latter are mostly concerned in nour- 

 ishing the organs of prehension. The inferior labial sup- 

 plies the skin and muscles of the lower lip. The inferior 

 coronary, leaving the facial at some distance from the 

 angle of the mouth, proceeds along the border of the 

 lower lip, and unites with its fellow of the opposite side. 

 The superior coronary pursues a similar course along the 

 border of the upper lip, uniting with its fellow and send- 

 ing a branch to the septum nasi. The lateralis nasi, and 

 the angular termination of the facial, supply the ala and 

 dorsum of the nose and the angle of the eye. 



The Infra-orbital is a branch of the internal maxillary, 

 which, passing along the infra-orbital canal, comes out at 

 the infra-orbital foramen, supplying the muscles of the 

 upper lip, and anastomosing witli the facial, transverse 

 facial, alveolar, buccal and ophthalmic arteries. 



The Transverse facial (trans vers alis faciei) comes from 

 the external carotid in the substance of the parotid gland ; 

 sometimes it is a branch of the temporal ; it runs parallel 

 to the duct of Steno, crossing the masseter muscle, supply- 

 ing the lateral parts of the mouth, and anastomosing with 

 the facial and infra-orbital arteries. 



The Veins correspond to the arteries and terminate in 

 the internal jugular. 



The Nerves of Prehension (Figs. 74, 97) belong to the 

 5th and 7th pair, which will be described under the heads 

 of organs of mastication and expression. 



SECTION II. 



ORGANS OF MASTICATION. 



These organs are divided into the passive and active. 

 The passive organs of mastication are 



THE TEETH. 



The teeth constitute the immediate agents in mastica- 

 tion, are the hardest portions of the body, and form an 



