FEACTUEES OF THE VAULT. 103 



to be followed by extravasation of blood, and this may collect 

 in the subcutaneous tissues and form the ordinary bruise so 

 frequently seen. 



If the haemorrhage be in a deeper plane, there is a tendency 

 for the blood to be diffused in the loose areolar tissue beneath 

 the aponeurosis, and a considerable quantity of blood may be 

 poured out, and the scalp may thus be raised so as to rest upon 

 a veritable blood cushion. Provided that sepsis is excluded, all 

 the blood will be eventually absorbed. 



In other cases the blood may be poured out between the 

 pericranium and the bone beneath. It is then generally spoken 

 of as a cephalhsematoma, and is often seen soon after birth as a 

 result of injury during the passage of the child's head along the 

 maternal channel. The pericranium is but loosely attached to 

 the bone except where it is continuous with the tissues at the 

 sutures. Hence it follows that in cephalhaematoma there may be 

 a complete concealment of a single bone, which has led to the 

 assumption that the bone most usually the parietal is absent. 



The pericranium is more firmly adherent over the temporal 

 bone than elsewhere, and it is rare to get a hsematoma beneath 

 it in this region. 



FRACTURES OF THE CRANIUM. 



These may consist of fractures of the vault or fractures of the 

 base, or of a fracture which runs from one into the other. 



Fractures of the Vault. The bones of the vault of the skull 

 for the most part are flat bones composed of two tables, an outer 

 and an inner, of compact tissue, and an intervening layer the 

 diploe of cancellous tissue. 



Four main sutures between these bones may be recognised in 

 the full-grown subject, any one of which may have to be dis- 

 tinguished from a fracture. Their exact position is therefore a 

 matter of some import. (See Fig. 5, p. 104.) 



The coronal, or fronto-parietal, has its summit at the bregma, 

 a point in the median antero-posterior plane of the skull where 



