The objective of this study is to present a potential mechanism for traumatic brain injury resulting from a lateral blunt impact to the head during SUV-to-pedestrian impact. We developed an AM50th percentile model of the human head, and the mechanical response predicted by the model was validated against available cadaveric test data. It was found that the traction force due to the inertia of the brain mass plays a key role in brainstem lesion prior to the primary contact as well as the local stress/strain distribution around the lateral ventricle immediately after the contact with a vehicle.