The San Francisco 49ers placed center Daniel Kilgore and cornerback Chris Cook on injured reserve Saturday and signed safety Bubba Ventrone to a one-year deal.

Kilgore, a fifth-round draft pick in 2011, has played in 40 NFL games over the past four seasons. All seven of his starts occurred this year. The 26-year-old played collegiately at Appalachian State.

Cook, 27, has three tackles and one pass breakup in six games this season. He also has two stops on special teams. He signed with the 49ers in March. He was originally drafted by the Minnesota Vikings in 2010 out of Virginia. In 40 NFL games (29 starts), he has 124 tackles, 34 pass breakups and one sack.