SriIEXOID EOXE. 



43 



The great wings, ala^ majoros, project outwards and upwards from 

 the sides of the body. The back part of each is placed horizontally, 

 and occupies the angle between the petrous and squamous portions of 

 the temporal bone ; from its pointed extremity it sends downwards a 

 short and sharp projection, the spinous process. The upper and fore 

 part is vertical, and three-sided, lying between the cranial cavit}-, the 

 orbit, and the temporal fossa. The cerchral surface of the great wing is 

 concave, and forms part of the middle fossa of the base of the cranium. 

 The external surface (temporo-zygomatic) is divided by a ridge into an 

 inferior part, which looks downwards into the zygomatic fossa, and an 

 elongated superior part, looking outwards, which forms a part of the 

 temporal fossa. The anterior surface looks forwards and inwards, and 

 consists of a quadrilateral orhital portion, which forms the back part 

 of the external wall of the orbit, and of a smaller inferior portion which 

 overhangs the pterygoid process, looks into the spheno-m axillary fossa, 

 and is perforated by the foramen* rotundum. The external margins 

 between the cerebral and external surfaces articulate with the temporal 

 and parietal bones ; anteriorly, the margin between the orbital and 

 external surfaces articulates with the malar bone. The margin below 

 this forms the upper part of the posterior boundary of the pterygo- 

 raaxillary fissure ; internally, the cerebral and orbital surfaces come 

 into contact at the outer border of the sphenoidal fissure ; and 

 superiorly, the cerebral, orbital, and external surfaces surround the 

 triangular area which articulates with the frontal bone. 



The small wings, alee minores {wiu//s of lugrassias), extend nearly 

 horizontally outwards from the fore part of the superior surface of the 

 body. The extremity of each is slender and pointed, and comes very 

 €lose to, but not into actual contact with, the great wing. The superior 

 surftice forms part of the anterior fossa of the base of the cranium, the 

 inferior overhangs the sphenoidal fissure and the back of the orbit. 



FiL 



Fig. 37.— The Sphenoid Bone from before. (A. T.) | 



The indications whei-e marked are the same as in the preceding iigiire. 17, marks the 

 anterior opening of the Vidian foramen or canal ; 18, the external or temi^oral surface 

 of the gi-eat wing ; 19, its orbital surface ; 20, the sphenoidal turbinated or spongy bone ; 

 above 20, the opening into the sphenoidal sinus ; 21, the sphenoidal spine ; 22, the 

 rostrum, and above 22, the inverted lamina, which fit with the edges of the vomer. 



