6 SuKcrcAL APPLIED A NATO My. [Chap, i 



general indisposition of the pericranium to form new 

 bone in other circumstances is frequently illustrated. 



Abscess in the scalp region may be situated 

 (1) above the aponeurosis, (2) between the aponeurosis 

 and the pericranium, and (3) beneath the pericranium. 

 Abscesses in the first situation must always be small 

 and comparatively insignificant, since the density of 

 the scalp tissue here is such that suppuration can 

 only extend with the greatest difficulty. Suppuration, 

 however, in the second situation (in the loose tissue 

 beneath the aponeurosis) may prove very sei-ious. 

 The laxity of this tissue offers every inducement to 

 the abscess to extend when once pus has found its 

 way between the aponeurosis and the pericranium. 

 Suppuration in this area may undermine the entire 

 scalp, whicli in severe and unrelieved cases nlay 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-frontalia 

 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 



