The Rams have lost five in a row, with Jackson limited to a little more than one half during that stretch, entering their game against the Miami Dolphins.
Rookie David Vobora started at linebacker in place of Will Witherspoon, who is nursing injuries to both shoulders. Rams coach Jim Haslett said Witherspoon would play on third down and in two-minute defense.
Vobora was the final overall pick of the draft.
The only Dolphins starter on the inactive list was linebacker Jason Allen (hand), who had been listed as probable. Rookie offensive tackle Jake Long (ankle), who was in the lineup, was the only other Dolphins' player on the injury report Friday.