Head and Neck. 409 



to the possibility of mistaking the raised border of a 

 cephalhsematoma for a depressed fracture and the means 

 of differentiating the one from the other. 



Fractures of the Base are generally parallel to 

 the direction of the force causing them, so that, in blows 

 or falls on the side of the head the direction will be, as a 

 rule, transverse, whereas in injuries received on the fron- 

 tal or occipital regions, it will be longitudinal. These 

 fractures may result from direct or indirect force the 

 direct being due to thrust wounds implicating the orbit, 

 the cribriform plate of the ethmoid, the sphenoid or rarely 

 the occipital bone, or they may be due, as metioned above, 

 to falls on the lower jaw, or feet, or to falls in which the 

 head strikes some yielding body such as soft earth, etc. 

 The indirect are due, according to Aron's law, to radia- 

 tion of the fissure, from the point struck, by the nearest 

 way to the base. In those instances in which there occurs 

 a fracture of the base, without one of the vault, the explan- 

 ation is, that the basal fracture occurs from compression, 

 i.e., that the skull bursts, as it were, at the lower segment. 

 As a rule, force applied to the frontal region produces, 

 when the base is affected, a fracture of the anterior fossa. 

 When applied to the parietal region it produces a fracture 

 of the middle fossa, or to the occipital region, the posterior 

 fossa. Among the symptoms of fracture of the base, are : 

 (1) Ecchymosis. Ecchymosis may be due to direct in- 

 jury to the soft parts without any involvement O'f the skull 

 whatever, and, when occurring in the region of the orbit, 

 the ecchymosis resulting from a purely local injury must 

 be distinguished from that following a fracture of the base. 

 In the former instance the bruise or "blackeye" appears 

 very shortly after the receipt of the injury, and, 'besides, if 

 the conjunctiva has been injured at the same time, discolor- 

 ation of the eyeball, which occurs, almost immediately, in 



