194 BONES OE THE CRANIUM. 



curving downwards and outwards. To it are attached the 

 internal lateral ligament of the lower jaw, the laxator 

 tympani, and the tensor or circumflexus palati muscles. 



This hone has a number of foramina. Beginning in front 

 and proceeding backwards, we observe, first, at the root of 

 the lesser wings, the foramen opticUm for the optic or nerves 

 of sight; second, the foramen rotundiim, in the base of the 

 greater wing, where it joins the body. This opens into the 

 pterygo-maxillary fossa, and transmits the superior max- 

 illary nerve. Behind it, about half an inch, is the foramen 

 ovale, which gives passage to the inferior maxillary nerve; 

 and a little posterior to this again is a small opening, the 

 foramen spinale, through which passes the middle menin- 

 geal artery. Between the lesser and greater wings is a long 

 slit, the foramen lacerum superius or orbitale, wide inter- 

 nally, narrow externally, and transmitting the third, the 

 fourth, the first branch of the fifth, and the sixth pair of 

 nerves, together with several filaments of the sympathetic 

 nerve and the ophthalmic vein. Between the posterior 

 part of the greater wing and the petrous portion of the 

 temporal bone there is another slit, the foramen lacerum 

 medius; and at the base of the pterygoid process, as stated, 

 the Vidian foramen. 



The structure of the sphenoid is cellular in the body and 

 bases of the processes, compact every where else. At about 

 the age of ten years the body is hollowed into cavities called 

 the sphenoidal sinuses. In front of them are two triangular 

 pyramidal bones, called, after their discoverer, the ossapyr- 

 amidalia Wisterii, or the sphenoidal turbinated bones. The 

 base of each of these is anterior, and connects with the eth- 

 nioidal bone and its cells; the apex is posterior, and unites 

 with the sphenoidal sinuses. These pyramids of Wistar 

 are found to be fused into the body of the sphenoid from 

 about the fifteenth to the eighteenth year. 



The development of this bone has been noticed to begin 

 from as many as twelve points of ossification, viz : 4 for the 

 body, 4 for the wings, 2 for the pterygoid processes, and 2 

 for the pyramids of Wistar. At birth the sphenoid is seen 



