When I was taking Hapkido karate, the sensei told us that, there are nerves right at the hinge of the jaw, on both sides of the face. Sensei said that these are like a light switch that controls the power to the brain.
And he said that, if you just hit the jaw with a halfway decent lick, and wiggle that jaw left to right, it will flip that switch and your opponent will be knocked right out on his feet.
I never have had the chance to try it in a fight but that is exactly what that black cop did. Not that much power in the punch but he flipped the switch on 'ol Aunt Jemima.
