The 49ers opened the practice window for running back Trenton Cannon on Wednesday, the team announced. They have 21 days to activate him from injured reserve.
Cannon left the field in an ambulance after a scary collision on the opening kickoff against the Seahawks on Dec. 5. He was chasing Seahawks returner DeeJay Dallas when he collided with teammate Talanoa Hufanga, whose thigh hit Cannon in the head as Cannon’s neck bent backward.
Cannon spent the night in a Seattle hospital for observation with a concussion, and the 49ers placed Cannon on injured reserve Dec. 11.
The 49ers also restored safety Doug Middleton to the practice squad from the injured reserve list and signed punter Ryan Winslow to the team’s practice squad. They waived quarterback Tyler Bray from the practice squad.