chap, ii.] BONY VAULT OF THE CRANIUM. 13 



before the age of four years. The anterior fontanelle 

 is the last to close, while the posterior is already filled 

 at t^ie time of birth. It is through or about the 

 anterior fontanelle that the ventricles are usually 

 tapped in paracentesis in cases of hydrocephalus. In 

 this operation the trochar is either entered at the sides 



Fig. 2. The Cranial Sutures. (After Gavoy.) 



of the fontanelle at a sufficient distance from the 

 middle line to avoid the sinus, or is introduced 

 through the coronal suture at some spot other than its 

 middle point. It may be noted that in severe hydro- 

 cephalus the coronal and other sutures of the vault 

 are widely opened. 



The condition known as cranio-tabes, a con- 

 dition assigned by some to rickets and by others 

 to inherited syphilis, is usually met with in the 

 vertical part of the occipital bone, and in the ad- 

 jacent parts of the parietal bones. In this condition 

 the bone is greatly thinned in spots, and its 



