REMOVAL OF THE BRAIN 



99 



protuberance. The saw should be used to divide the outer table 

 of the skull only. When the diploe is reached, the sawdust will 

 become red and moist, and the saw should then be abandoned. 

 The hammer and chisel are now brought into requisition, and by 

 short sharp strokes with these the inner table can readily be 

 split along the line in which the outer table of the cranium is 

 divided. When that has been done, insinuate the hook at the 

 end of the cross-bar of the chisel into the fissure in front, and 

 wrench off the skull-cap. 



Dura Mater Encephali. The brain is clothed by three 

 distinct membranes, which are termed the mentnges. From 

 without inwards they are (r) the dura mater; (2) the 

 arachnoid ; and (3) the pia mater. 



Vein Sub-arachnoid space and trabeculae 



" ~ Dura mater 

 ~~ -Subdural space 

 C "Arachnoid 

 Pia mater 



Artery* '' 



FIG. 29. Diagrammatic section through the Meninges of 



the Brain. (Schwalbe. ) 

 co. Grey matter of cerebral gyri. 



When the skull-cap is detached, the outer surface of the 

 dura mater, as it covers the upper surface of the cerebral 

 hemispheres, is exposed. It is rough, and dotted over with 

 bleeding points. If a portion is placed in water, its roughness 

 becomes still more manifest, and is seen to be due to a multi- 

 tude of fine fibrous and vascular processes by which it was 

 connected with the deep surface of the bones. The processes 

 were necessarily torn asunder t in 5 the removal of the skull- 

 cap. The bleeding points are mosi numerous aloiig th^ 

 median line, or, in other worcls, along the line of die superior 

 sagittal sinus (O.T. longitudinal) :. and j.f ;he liar. die, cf, the 

 knife is run from before JbacXwartis, so as to mafce. pressure? 

 along that line, a considerable^!! J|i0 6fj f bipod will ooze out, 



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