Chap, ii.] BONY VAULT OF THE CRANIUM. 15 



being in normal position (Fig. 2). The lambda, oi 

 point of junction of the lambdoid and sagittal sutures, 

 lies in the middle line, about 2f- inches above the 

 occipital protuberance. The lambdoid suture is fairly 

 represented by the upper two-thirds of a line drawn 

 from the lambda to the apex of the mastoid process 

 on either side. The coronal suture lies along a line 

 drawn from the bregma to the middle of the zygo- 

 matic arch. On this line, at a spot about on a 

 level with the external angular process of the frontal 

 bone, and about \\ inches behind that process, is 

 the pterion, the region where four bones meet, viz. the 

 squamous bone, the great wing of the sphenoid, the 

 frontal and parietal bones. The summit of the squa- 

 mous suture is 1| inches above the zygoma. 



In the normal subject all traces of the ibntanelles 

 and other unossitied parts of the skull disappear 

 before the age of four years. The anterior fontanelle 

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

 at the 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 

 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-tafoes, 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 adjacent parts of 

 the parietal bones, but especially in the posterior 

 inferior angles of these bones. In this condition the 

 bone is greatly thinned in spots, and its tissue so 

 reduced that the affected district feels to the finger as 



