With their once-abundant inside linebacking corps down to two players, the 49ers signed former Cal product and long-time Green Bay Packer Desmond Bishop.

Bishop, 30, played for Green Bay from 2007-12. He was with the Vikings in 2013 and on the Cardinals roster last season. His best season came in 2011 when he finished with 115 tackles and had five sacks for the Packers. He worked out for the 49ers last week.

To make room for Bishop, the 49ers placed WR Kassim Osgood on injured reserve with a broken bone in his hand.

The 49ers played most of the season without all-star linebackers Patrick Willis and NaVorro Bowman, both of whom are currently on injured reserve. Meanwhile, rookie Chris Borland was forced out of Sunday’s game in Seattle with an ankle injury and his availability for Saturday against the Chargers is in doubt. Borland leads the 49ers in tackles despite the fact that he only became a starter in Week 7.

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His injury left Michael Wilhoite – who briefly left the game – and seldom-used Nick Moody as the team's inside linebackers. Moody played well in his first extensive action, finishing with five tackles as well as a controversial hit on Seahawks quarterback Russell Wilson.

In addition, the 49ers added tight end Xavier Grimble to the practice squad. The 49ers were down to two tight ends Sunday after Garrett Celek left the game with an ankle sprain. Grimble, who spent time on San Francisco's practice squad earlier this year, could be brought to the active roster if the 49ers are short at the position for Saturday's game against the Chargers.