jo SURGICAL APPLIED ANATOMY. [Chap, in 



skull and dura mater at the part struck, and having 

 an exact resemblance to the coagulum found after 

 violent blows on the head." Tillaux has demonstrated 

 that the adhesions between the dura mater and the 

 bone are particularly weak in the temporal fossae, 

 the most usual site of meningeal haemorrhage. 



When blood is poured out between the dura mater 

 and the bone in cases of fracture, the vessel that, as a 

 rule, gives way, is the middle meningeal artery 

 In thirty-one cases of such haemorrhage, this vessel was 

 the source of the bleeding in twenty-seven instances 

 (P. Hewett). The vessel having passed through the 

 foramen spinosum, divides into two branches ; the 

 anterior, the larger, runs upwards across the anterior 

 inferior angle of the parietal bone ; the posterior runs 

 backwards, with a horizontal sweep across the squa- 

 rnous bone. 



Mr. Jacobson has shown that the branches of the 

 artery are more frequently ruptured than the trunk. 

 The vessel is very frequently torn as it crosses the 

 anterior angle of the parietal bone. There are many 

 reasons for this : the bone where grooved by the 

 artery is very thin ; the artery is often so embedded 

 in the bone that fracture without laceration of the 

 vessel would hardly be possible ; and lastly, the par- 

 ticular region of the artery is a part of the skull 

 peculiarly liable to be fractured. Mr. Jacobson shows 

 that the artery may be ruptured by a foi-ce that does 

 not fracture the skull, but merely leads to detach- 

 ment of the dura mater. (See page 29.) Failing this 

 vessel, the most frequent source of extra-meningeal 

 haemorrhage is the lateral sinus, for reasons that will 

 be obvious. 



With regard to the blood sinuses formed by the 

 dura mater, nothing remains to be added to what has 

 been already said (page 12), except, perhaps, to 

 observe that the relations between the internal 



