SANTA CLARA, Calif. -- The incremental injury news was positive Thursday for the San Francisco 49ers.Right tackle Anthony Davis (shoulder) practiced on a limited basis after sitting out Wednesday. That is a good sign he will be able to play Sunday against Houston. The Texans have blitzed more than any team in the NFL this season. Thus, Davis' role will be vital.Star inside linebacker Patrick Willis (groin), tight end Vernon Davis (hamstring) and No.