THE MFXHANICS OF BRAIN INJURIES 



A. H. S. HOLBOURN, D.Phil. 



Research Physicist^ University Laboratory of PhysioUtgy and 

 Department of Surgery, Oxford 



Introduction 



THERl^ is some truth in almost all the theories of the 

 mechanisms of brain injuries due to violence,^- ^^' ^^ but in 

 the writer's view '■ "^ only skull bending, fracture, and 

 rotation ^ of the head are important. The physicist would 

 attribute the comparative failure of most of the theorists to their 

 wrong method of approaching the problem, in that they began 

 by fastening their attention on a particular mechanism (e.g., 

 coup and contrecoup, or production of cerebral anemia). The 

 physicist's initial assumption is that damage to the brain is a 

 consequence, direct or indirect, of the movements, forces, and 

 deformations at each point in the brain. The movements, forces, 

 and deformations are not independent ; so that it is sufficient 

 to express everything in terms of deformations. These are 

 worked out with strict adherence to Newton's laws of motion, 

 but with approximations to the constitution and shape of skull 

 and brain. Hence further advances can come only from making 

 better approximations. 



Tlie Forces to be Considered 



As a consequence of the principle of superposition, it is 

 reasonal)ly correct to assume, in this particular problem, that 

 each cause produces its own independent injury. These causes 

 may be regarded as (a) forces on the brain resulting from bend- 

 ing of the skull, (b) forces resulting from fracture of the skull 



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