Even to N.F.L. fans used to seeing players injured, sometimes severely, the scenes at NRG Stadium in Houston were disturbing and are once again raising concerns about how effectively players are checked for concussions.
As Texans quarterback Tom Savage threw a pass from his own end zone in the second quarter on Sunday, he was hit by Elvis Dumervil of the San Francisco 49ers and landed hard on the turf.
It seemed at first like another hard hit in a sport full of them but the immediate aftermath was more unusual. Savage rolled onto his back and lifted up his hands, which visibly quivered.