Young has been bothered by a knee injury since training camp, and sat out of practice on Wednesday. However, his apparent step forward on Thursday means that the Lions only have one player on their roster, defensive tackle Corey Williams, who was not active in practice.
Avril was a limited participant on Wednesday, but has been practicing all week despite a sore back. He is expected to start on Sunday, and the chances of that certainly look better after getting a full day in on Thursday.
Linebacker Travis Lewis was also a full participant for the second straight day, while safety Louis Delmas, defensive tackle Sammie Hill, tight end Brandon Pettigrew and safety Amari Spievey joined Young as limited participants.
Delmas hasn't played this season, after undergoing knee surgery on Aug. 7. However, he is on track to make his season debut on Sunday against the Philadelphia Eagles, according to Dave Birkett of the Detroit Free Press.