THE SKULL THE CEANIUM 267 



os vespiforme, das Wespenbein, from the Greek, Latin, and German 

 words for a wasp. 



Articulation. The sphenoid articulates with the occipital, the 

 temporals, the parietals, the frontals, the palatines, the ethmoid, and 

 the vomer. 



Muscular Attachments. The following muscles are attached to 

 the sphenoid : to the temporal surface of the alisphenoid, the tem- 

 poral; to the orbital surface of the orbitospheuoid, the external ptery- 

 goid and most of the small ocular muscles ; to the external pterygoid 

 fossa, the internal pterygoid ; to the basisphenoid, the pharynx ; and 

 to its scaphoid fossa, the tensor and levator palati muscles. 



Ossification. The different primary centres of ossification co- 

 alesce to form eight elements, namely, the two orbitosphenoids, the 

 two alisphenoids, the two pterygoids, the presphenoid, and the basi- 

 sphenoid. At birth the orbitosphenoids have joined the presphenoid 

 and the alisphenoids have coalesced with the basisphenoid ; the ptery- 

 goids, however, are still partially distinct elements, the separating 

 sutures dividing the external pterygoid fossae from end to end and 

 meeting the thin inner margins of the vaginal processes on a line with 

 the foramina ovalia. 



VARIATIONS IN THE SPHENOID. 

 VARIATIONS IN SIZE. 



The following measurements show the differences in size observed 

 in twenty-five sphenoids : 



(1) The maximum length is the distance from the anterior end of 

 the orbitosphenoid to the posterior border of the basisphenoid ; 



(2) The maximum width is the distance between the outer edges of 

 the tips of the parietal angles ; 



(3) The maximum height represents the distance from the edge of 

 the hamular process to the tip of the parietal angle, taken at right 

 angles to the inferior surface of the bone. 



On the superior surface are measured : 



(4) The median length of the presphenoid ; 



(5) The distance between the outer edges of the optic foramina ; 



(6) The distance between the tips of the orbitosphenoids ; 



(7) The distance from the anterior edge of the parietal angle to 

 the extreme posterior outer angle of the alisphenoid ; 



