Watch the Zapruder film. As JFK is leaning forward, the last shot took off the back of his head. His head is flung back, while everyone else is stationary.
In one of the AP pictures that show SS Clint Hill climbing on back of the Presidential limo, you clearly see a bullet hole in the front windshield. (The windshield was later removed from the limo. )
I am not into conspiracies, but the idea that the shots all came from up and behind seems to defy logic and physics.
The crack in the windshield caused by one of the bullet fragments fired from the rear is on post 217. The other fragement hit the inside upper windshield trim. The second bullet which caused this damage and injury had broken at the cannelure.
The injury to the front of Kennedy’s head is on post 276. It also shows the two inch push from the rear on impact.