  Brain injuries are a major reason for mortality and morbidity following
trauma in sports, work and traffic. Apart from the trauma at the site of impact
(coup injury), other regions of the brain remote from the impact locations
(non-coup) are commonly affected. We show that a screw theory-based method can
be used to account for the combined effect of head rotational and linear
accelerations in causing brain injuries. A scalar measure obtained from the
inner product of the motion screw and the impact screw is shown to be a
predictor of the severity and the location of non-coup brain injuries under an
impact. The predictions are consistent with head impact experiments conducted
with non-human primates. The methodology is proved using finite element
simulations and already published experimental results
