408 Anatomy Applied to Medicine and Surgery. 



besides, in a fracture, no amount of rubbing with a sponge 

 will remove the line of blood (bright red in recent in- 

 juries, but darker in color in older ones) effused between 

 the edges of the fractured bone. Punctured wounds of 

 the skull may be inflicted with a sharp-pointed instrument 

 such as the blade of a knife, etc., and, if the instrument 

 inflicting the wound, be driven into the bone at 

 right angles, there may be neither splintering nor depres- 

 sion of the inner table ; whereas, if the instrument be dull, 

 such as a blunt-pointed nail, the end of a cane, etc., there 

 may be extensive comminuting of the inner table. De- 

 pressed fractures usually cause a greater degree of splin- 

 tering of the inner table than one would think, judging 

 from the size of the depression of the outer table. This 

 is probably due to the fact, as pointed out by Teevan, that 

 the bone yields, first, on the side of extension, i.e., that the 

 table exposed to most extension gives way first, just as in 

 breaking a stick over the knee. Possibly the diffusion of 

 the force as it passes through the diploe and the brittle 

 nature of the inner table are contributing factors. The 

 elasticity of the outer table causes a recoil which lessens 

 the depression of this table; whereas, in the case of the 

 inelastic inner table no such recoil occurs and, hence, this 

 table lomains more depressed than the outer. The frontal 

 sinuses appear, first, about the age of seven as prolonga- 

 tions from the anterior ethmoidal cells, but do not often 

 attain any great size until after the twenty-fifth year of 

 age. A depressed fracture in the region of these sinuses 

 may not cause any splintering of the inner table, yet these 

 wounds should be carefully examined in every case to as- 

 certain the existence of a sinus, since, even in advanced 

 adult age, the frontal sinus may be undeveloped or may 

 exist on one side only. Attention has already been drawn 



