82 ELEMENTARY ANATOMY. [LESS. 



this is the foramen rotundum, through which passes the 

 second branch of the fifth nerve. Behind this is a larger 

 foramen (termed from its shape foramen ovale}, which gives 

 exit to the third branch of the fifth nerve. On each side of 

 the sella turcica, at its hinder part, is a groove for the carotid 

 artery. This groove is bounded in front and externally by a 

 small tapering piece of bone which is called the lingula 

 sphenoidalis, and which is situated between the body of the 

 bone and the greater ala. 



f 



"FIG. 86. MAN'S SPHENOID BONE SEEN FROM ABOVE. 



a, its greater wing the lower letter a points to that downward continuation of 

 the great wing which is called the external pterygoid process ; bs, its body 

 showing a cut surface behind, where it has been separated from the occipital 

 bone ; pc, the clinoid plate, bounding the pituitary fossae behind ; ps, the 

 anterior, or pre-sphenoidal part of the body of the bone ; o, lesser or orbital 

 wing ; /, internal pterygoid process ; i, optic foramen ; 2, sphenoidal fissure ; ' 

 3, foramen rotundum ; 4, foramen ovale : 5, groove for the carotid artery. 



The greater ala passes up between the squamosal and the 

 frontal to the parietal bone, and forms the anterior part of the 

 temporal fossa and the hinder, outer part of the bony orbit. 



The downwardly extending plate is called the external 

 pterygoid T process. The internal pterygoid process is more 

 slender, terminating below in a hooked-Tike, or hamular, pro- 

 cess. The two internal pterygoid processes form what have 

 been fancifully called the legs of the sphenoid. Between the 

 internal and external pterygoid process of each side is a space 

 called the pterygoid fossa, which is closed behind by a palate 

 bone. 



From the anterior part of the body the much smaller wings 

 called "orbital" project outwards, one on each side. The 



1 From Ti-Ttpf?, a wing 



