With Chris Borland s ankle injury the latest blow to a depleted linebacker corps, the 49ers have signed linebacker Desmond Bishop, a league source said Tuesday.
Bishop is a Cal product who won a Super Bowl ring with the 2010 Green Bay Packers. He spent time with the Arizona Cardinals this season, but he appeared in no games before being cut Dec. 1.
He was on the Minnesota Vikings injured-reserve list last season because of a torn anterior cruciate ligament, and his six-year Packers tenure ended after he missed the 2012 season with a hamstring injury.
Borland is likely out of Saturday s game against the Cardinals because of an ankle injury he sustained on Eric Reid s interception return before halftime of Sunday s 17-7 loss at Seattle. Borland has started the past eight games in place of Patrick Willis, who is out for the season following toe surgery.
That inside-linebacker unit also saw Michael Wilhoite leave for a bit during Sunday s game with an injury, leaving seldom-used Nick Moody to man the middle and prompting safety Antoine Bethea to move up from his position.