THE STRUCTURE OF THE HUMAN SKULL. 



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If a vortical and transverse section be taken through the 

 cranium, in such a manner that the plane of the section shall 

 traverse both external auditory meatuses, the skull will be 

 divided into two unequal portions — an anterior, larger, and a 

 posterior, smaller. The former, if viewed from behind, will 

 present the appearance represented in Fig. 48. 



Fig. 48. 



Fig. 48. — Anterior half of the skull ot a young person (six or seven years of age) trans- 

 versely bisected. The temporal bone (27) on each side is left in outline, and the 

 contour of the alisphenoid is supposed to be seen through it. — IT, optic foramina be- 

 tween the roots of the orbito-sphenoids ; V, foramen ovale for the third division of 

 the trigeminal; N indicates the nasal chamber; Mx is placed in the buccal chamber. 



A stout median floor (B8) whence lateral continuations 

 (AS) are prolonged to meet an arched roof (Pa), divides a 

 capacious upper chamber, which, during life, lodged a part of 

 the brain, from a lower chamber, formed by the bones of the 

 face. This lower chamber itself is again separable into two 



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