(1) High-speed cinematography is useful in the evaluation of the movements of the head, neck, and body following impact. (2) The head of the experimental animal moves several millimeters even though it may be relatively fixed. Such movements are sufficient to impart high accelerative forces to the head. (3) Flexion and extension at the craniospinal junction appear to be a minor factor in the explanation of concussion. Certainly, concussive effects are obtained without any apparent movements of the head and neck neighborhood. (4) High-speed cinematography shows the potential for multiple injuries of the head and body in one accident. Several head impacts may follow one another during a few milliseconds following impact.