THE SKULL THE CKANIUM 



273 



completely coalesced with the sphenoid. The ethmoidal crest is con- 

 tinued on the inferior surface of the anterior sphenoid as the sphe- 

 noidal rostrum. The sphenoidal fissure extends outward and sepa- 

 rates completely the small and great wings. 



The anterior sphenoid as a whole is bent downward from the plane 

 of the posterior sphenoid. 



The pterygoid processes arise from the body of the bone in 

 common with the great wings and posterior to the anterior sphenoid, 

 with which they are not connected. Each process consists of two 

 parts, called plates ; the outer plate corresponds with the part of the 

 alisphenoid of the cat which bears the small external pterygoid pro- 

 cess ; the inner plate corresponds with the pterygoid bone. The 

 anterior edges of the two plates are united, except at the inferior part, 

 where they diverge and articulate with the pyramidal process of the 



FIG. 196. 



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THE SPHENOID BONE. INFERIOR ASPECT. 



1, sphenoidal rostrum ; 2, spheno-turbiual ; 3, opening of sphenoidal sinus; 4, orbital margin of spheno- 

 turbinal ; 5, spheuoidal fissure ; 6, pterygoid process ; 7, vaginal process ; 8, bristle passed through basipharyngeal 

 canal; 9, bristle through pharyiigeal canal; 10, sphenoidal crest; 11, orbital surface of great wing; 12, temporal 

 surface ; 13, spheno-maxillary crest ; 14, infratemporal crest ; 15, zygomatic surface ; 16, angular spine ; 17, 

 squamous border ; 18, foramen rotundum ; 19, Vidiau canal ; 20, pterygoid fissure ; 21, foramen ovale ; 22, foramen 

 spinosum. 



palatine bone. Their posterior edges are separated by the external 

 pterygoid fossa. The vaginal process from the root of the inner plate 

 is well marked, and, owing to the antero-posterior compression of the 

 skull, articulates by its edge with the vomer, completing with it a 

 dorsal longitudinal basipharyngeal canal. Its ventral surface presents 

 a groove which the palatine bone converts into a pharyngeal canal. 



Below the orbital surface (Figs. 194, 196) of the great wing and 

 separated from it by a spheno-maxillary crest is the external opening 



18 



