Jackson, who rushed for 160 yards and three touchdowns in last Sunday's 34-14 win over the Dallas Cowboys, was sidelined with a strained right thigh muscle. He leads the Rams with 508 yards rushing and 25 receptions.
Morris gained a career-high 138 yards rushing in the first half of Monday night's 41-7 win over the Denver Broncos, but sat out the rest of the game with a knee injury.
Starting tackle Nick Kaczur and defensive end Jarvis Green were inactive for the second straight week for the Patriots with injuries. Other inactives for New England were wide receiver Matthew Slater, cornerback Lewis Sanders and linebackers Eric Alexander and Shawn Crable.
For St. Louis, the other inactive players were defensive tackle Adam Carriker, cornerback Tye Hill, safety Todd Johnson, guard Roy Schuening, wide receiver Drew Bennett and tackle John Greco. Brock Berlin was listed as the third quarterback.