Just as he was playing well in tonight’s preseason game vs the Ravens, QB Tarvaris Jackson left the game with a knee injury.  The injury took place late in the first quarter when Jackson scrambled, and then was hit on a tackle by Ravens LB Antwan Barnes.  Jackson was running around right end on a scramble before Barnes caught up him and hit him on the leg.  The extent of the injury was not immediately known, but the Vikings said Jackson would not return to the game.  Jackson was 7-for-11 for 82 yards and a touchdown.