49ers defense takes another blow

SANTA CLARA, Calif. -- An already thin-San Francisco 49ers defense took another blow Sunday when starting safety Antoine Bethea departed early in Sunday's home game against Denver with a concussion. He will not return to the game, the team said.

Bethea went down after a block from Denver rookie receiver Cody Latimer. Players summoned team personnel to the field as soon as Bethea went down. 49ers coach Jim Harbaugh was on the field as well.

Bethea was able to walk off the field on his own power. Bethea was signed this year as a free agent after six seasons. He never missed a regular season game in six seasons with the Colts. Bethea was just one of six 49ers starters to play Sunday because of various ailments.