Jackson was injured during practice Saturday morning, when he caught a pass and stumbled to the ground without making contact with other players. Jackson needed help to the sideline, and moments later, a cart came and took him to the workout facility.
Linebacker Stewart Bradley also didn't practice Sunday because of hamstring spasms and is considered day to day. He missed the 2009 season with a torn anterior cruciate ligament that he sustained during a training-camp practice last year.
The Associated Press contributed to this report.