THE SKULL 285 



i. The pterygoids are a pair of narrow vertical 

 plates of bone, attached to the base of the 

 skull at the junction of the basi- sphenoid with 

 the ali-sphenoids. The posterior border of 

 each pterygoid is free, and ends below in the 

 curved hamular process, while the anterior 

 border unites with the palatine and ali-sphe- 

 noid. On the outer side of the pterygoid, 

 between it and the external pterygoid process 

 of the ali-sphenoid, is the triangular pterygoid 

 fossa. 



ii. The palatines are a pair of nearly vertical plates 

 of bone, attached above to the ventral border 

 of the pre-sphenoid, and behind to the ptery- 

 goids and ali-sphenoids, thus completing the 

 anterior boundaries of the pterygoid fossae. 

 They form the side- walls of the posterior 

 narial passage, which they separate from the 

 orbits. In front they are produced inwards 

 into the horizontal palatal processes, which 

 meet each other in the median plane in the 

 roof of the mouth, opposite the grinding teeth, 

 forming the posterior third of the bridge of 

 bone supporting the hard palate. 



iii. The maxilla are a pair of large irregular bones 

 forming a large part of the skeleton of the 

 upper jaw and of the face. 



The body, or alveolar portion, of each 

 maxilla projects into the front part of the orbit, 

 and is excavated by the alveoli or sockets for 

 the grinding teeth. Its inner surfaceis covered 

 by the palatine behind ; and in front is pro- 

 duced inwards into the horizontal palatal 

 process, which meets its fellow in the median 

 plane, and forms the anterior part of the bony 

 bridge supporting the hard palate. 



From the outer side of the body arises the 

 stout zygomatic process, which is prolonged 



