Chap, i.] THE SCALP. ' 7 



The extravasation of blood above the aponeurosis 

 must be of a limited character, while that beneath it 

 may be very extensive. It fortunately happens, how- 

 ever, that the cellular tissue between the aponeurosis 

 and the pericranium contains but very few vessels, 

 and hence large extravasations in this tissue are un- 

 common. 



Extravasations of blood beneath the pericranium 

 are generally termed cephalhsematomata, and are of 

 necessity limited to one bone. They are usually con- 

 genital, are due to pressure upon the head at birth, 

 and are thus most commonly found over one parietal 

 bone, that bone being probably the one most exposed 

 to pressure. Their greater frequency in male children 

 may depend upon the larger size of the head in the 

 male foetus. Such extravasations in early life are 

 encouraged by the laxity of the pericranium, and by 

 the softness and vascularity of the subjacent bone. 



In the temporal region, or the region corre- 

 sponding to the temporal muscle, the layers of soft 

 parts between the skin and the bone are somewhat 

 different from those that have been already described 

 as common to the chief part of the scalp. There is a 

 good deal of fat in the temporal fossa, and when this 

 is absorbed it leads to more or less prominence of the 

 zygoma and malar bone, and so produces the project- 

 ing " cheek bones " of the emaciated. The temporal 

 muscle above the zygoma is covered in by a very 

 dense fascia, the temporal fascia, which is attached 

 above to the temporal ridge 011 the frontal and pari- 

 etal bones, and below to the zygomatic arch. The 

 unyielding nature of this fascia is well illustrated by 

 a case recorded by Denonvilliers. It concerned a 

 woman who had fallen in the street, and who was 

 admitted into hospital with a deep wound in the 

 temporal region. A piece of bone several lines in 

 length was found loose at the bottom of the wound. 



