THE BONES OF THE HEAD 



85 



and is on a level with the anterior part of the upper surface of the 

 body ; and a lower, slender and compressed from before backwards, 

 which arises from the anterior part of the side of the body. The 

 wing is triangular and flattened from above downwards. The 

 superior surface, smooth and somewhat concave, forms the back 

 part of the anterior cranial fossa. The inferior surface overhangs 

 the sphenoidal fissure, and forms the back part of the roof of the 

 orbit. Externally the wing ends in a slender, pointed extremity, 

 which lies very near the great wing, but does not as a rule touch 



Opening of Sphenoidal Sinus 

 Sphenoidal Fissure 



Ethmoidal Spine 



Optic Foramen 



Temp. Div. of Ext. 

 Surf, of Great Wing 



Vidian C«nal — 



Zygom. Div. of Ext. 

 Surf of Great Wing 



spinous Process 



External Pterygoid Plate 



Hamular Process 

 Internal Pterygoid Plate 

 Sphenoidal Spongy Bone' 



Vaginal Process' 



^- Foramen Rotnndum 



NSphen.-maxilL Surf, 

 of Great Wing 

 '^•Sphenoidal Crest 



^ Pterygoid Notch 

 Pterygo-palatine Groove 

 r^ostnim 



Fig. 54. — The Sphenoid Bone (Anterior View). 



it, though it may do so. The anterior border is thin and serrated 

 for the orbital plate of the frontal. The posterior border, smooth, 

 thick, and round, corresponds with the Sylvian fissure of the 

 cerebrum, from which circumstance it is known as the Sylvian 

 horde-. It forms at either side the line of demarcation between 

 the anterior and middle cranial fossae, and terminates internally 

 in the anterior clinoid process for a portion of the tentorium 

 cerebeUi and the interclinoid ligament. 



Between the anterior clinoid process and the side of the olivary 

 eminence is the semicircular carotid notch, which is the anterior 



