6 SURGICAL APPLIED ANATOMY. [Chap. i. 



way between the aponeurosis and the pericranium. 

 Suppuration in this area may undermine the entire 

 scalp, which, in severe and unrelieved cases, may rest 

 upon the abscess beneath as upon a kind of water- 

 bed. As in scalp wounds the aponeurosis is often 

 divided, and as suppuration may follow the injury, it 

 will be seen that the chief danger of those lesions 

 depends upon the spreading of such suppuration to 

 the area of lax connective tissue now under notice. 

 The significance of a small amount of bare bone in a 

 scalp wound is not so much that evils will happen to 

 the bone, but that the aponeurosis has been certainly 

 divided, and the dangerous area of the scalp opened 

 up. Suppuration, when it occurs in this area, is only 

 limited by the attachments of the occipito-frontalis 

 muscle and its aponeurosis, and therefore the most 

 dependent places through which pus can be evacuated 

 are along a line drawn round the head, commencing 

 in front, above the eyebrow, passing at the side a 

 little above the zygoma, and ending behind at the 

 superior curved line of the occipital bone. The 

 scalp, even when extensively dissected up by such 

 abscesses does not perish, since it carries, as above 

 explained, its blood supply with it. The abscess is 

 often very slow to close, since its walls are prevented 

 from obtaining perfect rest by the frequent movement 

 of the epicranial muscle. To mitigate this evil, and 

 to ensure closing of the sinuses in obstinate cases, 

 Mr. Hilton advises that the whole scalp be firmly 

 secured by strapping, so that the movement of the 

 muscle is arrested. 



Abscess beneath the pericranium must be limited 

 to one bone, since the dipping-in of the membrane at 

 the sutures prevents a more extensive spreading of 

 the suppuration. 



Ileematomata, or blood tumours of the 

 scalp region, occur in the same localities as abscess. 



