FRACTURES OF THE CRANIAL BONES. 105 



Sd. Punctured fractures. 



4th. Compound fractures. 



6th. Fracture of external table only. 



6th. Fracture of the internal table only. 



1. Simple Fissure. — In this form there is no wound of the soft 

 parts, and the broken pieces preserve their proper level ; and if 

 there be no accompanying injury to the parts within the cranium, 

 it is not necessary to do more than guard against the occurrence 

 of inflammation ; but the force which breaks the bone may cause 

 separation of the dura mater, laceration of the brain, extravasa- 

 tion of blood within or upon it, or above and below the dura 

 mater ; or a mere crack in the outer table, with fracture and 

 depression of the inner table. There may be immediate con- 

 cussion of the brain ; or inflammation of it and its membranes, 

 may subsequently appear to a dangerous or even fatal extent. 



2. Simple Fracture, loith Depression. — In this form there will 

 be an inequality of the surface of the skull, varying in extent 

 according to the size of the depression, and generally associated 

 with a bruise of the skin. Sometimes the fragments are un- 

 yielding, and sometimes they are moveable. A condition of the 

 skin of the head is occasionally seen, which is apt to lead 

 one to suppose that the depression is much greater than it 

 is in reality, or to think that the bone is broken, when no 

 fracture exists. This is a swelling caused by extravasation, 

 and it occurs in this manner: — A blow is inflicted by a flat 

 instrument ; this blow is sufficient to deaden and paralyze the 

 vessels of the part itself, which remains firmly compressed; 

 but into the surrounding areolar tissue blood becomes extra- 

 vasated, raising the soft parts to a considerable extent. This 

 swelling is remarkably firm, and this condition should always be 

 kept in mind, or the practitioner may think there is a fracture 

 where none exists, or that the depression of fracture is much 

 greater than it is in reality. 



Fracture with depression will be attended by other symptoms 

 than the local ones above described, namely, by compression of 

 the brain; and when a depressed piece of bone occasions the 

 compression, the symptoms present themselves on the occurrence 

 of the injury ; but compression may arise from other results of 

 an injury to the head than fracture. For example, an animal 

 has received a blow on the head which may stun him ; he re- 



