THE CRANIUM 29 



the condyles glide too far forward and slip in front of the fossa, 

 making it impossible to close the mouth. To correct this con- 

 dition (or " reduce the dislocation") press the jaw forcibly down- 

 ward and backward with the thumbs placed upon the molar teeth. 

 (First wrap the thumbs with a napkin to protect them, as the 

 mouth will close suddenly.) 



POINTS OF INTEREST IN CONNECTION WITH THE 

 SKULL AS A WHOLE 



THE CRANIUM 



The cranium is a firm, strong case for the brain, composed 

 largely of flat bones, the layers of these flat bones being called the 



B REG MA 



ANTERIOR NASA 

 SPINE 



PROSTHIO 



GNATHI 



BELION 



MBDA 



FIG. 20. THE VERTEX AND SIDE OF THE SKULL. (Gerrish.) 



tables of the skull. The innermost table is very brittle and may be 

 fractured by a blow which does not break the outer one, and 

 owing to this brittleness it is called the vitreous, or glassy layer. 



Observing the illustrations, or better, with the skull in the 

 hand, the student may trace the frontal, two parietal, and 

 occipital bones forming the vault of the skull, or the vertex; and at 



