THE BONES OF THE HEAD 



83 



margin of the cribriform plate of the ethmoid. The sella turcica 

 is bounded posteriorly by a prominent quadrilateral plate of bone, 

 called the dorsum sellae or dorsum ephippii (back of the saddle), 

 which is directed forwards and upwards. The antero-inferior 

 surface of this plate overhangs the sella turcica, and the postero- 

 superior surface, called the elivus (slope), is inchned downwards 

 and backwards to become continuous with the basilar groove of 

 the occipital. The elivus lodges the upper part of the pons Varolii 

 and the basilar artery. The antero-superior border of the dorsum 

 sellae presents at either side the posterior clinoid process for a portion 



Limbus Sphenoidalis 

 Mid. Clinoid Process 

 Oplic Foramen \ 

 .\nt. Clinoid Process \ 

 Sphenoidal Fissure \ '• \ 



Ethmoidal 



T o u -J 1 Spine Optic Groove 



Jugum Sphenoidale "^ 



\ \ < Olfactory Groove 



', i ! ' 01i\'ary Eminence 



\ . I 1 



, '■ ; .' _/ f Carotid Notch 



\ ', ; ; / / / Small Wing 

 \ i • ; / .•■ / .' Sylvian Border of Small Wing 

 \ \ : .' ; ." / ;■ .• Great Wing 



Foram. Rotundum T^~ — ~ 



Foramen Vesalii "b'-^^^S^ 



Foramen Ovale 



Foram. Spinosnm 



Canaliculus Innominatus j : | 



Lingula | .' • 



Cavernous Groove ! ! 



Post. Clinoid Process I 



Clivns 



\ 



V Spinous Process 

 Notch for 6th Cranial Nerve 

 Posterior Petrosal Process 

 Dorsum Sellz 

 Sella Turcica 



Fig. 53. — The Sphenoid Bone (Superior View). 



of the tentorium cerebeUi and the interclinoid ligament, which 

 latter connects it with the anterior clinoid process, and is some- 

 times ossified. On each lateral border of the dorsum seUae, a little 

 below the posterior clinoid process, is a notch, which transmits the 

 sixth cranial nerve. At the lower end of each lateral border there is 

 a projection, called the posterior petrosal process, which articulates 

 with the apex of the petrous portion of the temporal, and bounds 

 internally the foramen lacerum medium. 



The inferior surface of the body is limited it either side by 

 the internal pterygoid plate of the pterygoid process. In the 

 middle line it presents a vertical, antero-posterior ridge, called 



