Et encore des extraits :
« Dr. Petty explained it this way : »The head snap to the rear, in the view of the panel, was that this was an automatic, involuntary reaction on the part of the President’s nerves and muscles. There was a blast inside the head, the nerves were fired off, and the muscles were set into action. The muscles in the back are stronger than the muscles in the front and so therefore the head moved backward.« »
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The key point here is that this complex rearward movement is not compatible with a direct hit of a bullet from the right front. The head does not snap backward rapidly the way it snapped forward, even though it was perfectly free to do so. Rather the head starts moving backward slowly and gains momentum over several frames. There is no cloud of brain matter to the rear as there was to the front. There is no damage to the left hemisphere of his brain, as there would have to be with a hit from the right. There is no cone of tiny fragments going from right to left in the brain, and no exit wound on the left side. No, the rearward motion was of JFK’s entire upper torso, with the head just moving along with the neck. It is a vicious recoil of sorts from the exploding right side of his head. Such a movement could have been caused by a mechanical recoil from the particles that exploded frontward out of his head (the so-called »jet effect« ), by some sort of neurological reaction (sometimes called a »neuromuscular spasm« ), or a combination of both. The available data strongly suggest that it was indeed a combination of effects, whose detailed contributions will probably never be known with certainty. »