Bronson out of Niners' depleted secondary

Updated: October 29, 2003, 6:46 PM ET

SANTA CLARA, Calif. -- Safety Zack Bronson is expected to miss the San Francisco 49ers' game against St. Louis on Sunday with a bulging disk in his back.

Bronson has started every game this season. He was hurt early in the 49ers' loss to Arizona last Sunday.

The 49ers also will be without top reserve safety Ronnie Heard, who sprained his left knee against the Cardinals.

John Keith is expected to start in Bronson's place. Keith has started six games in his four seasons with San Francisco, but began the season on the practice squad.

This story is from ESPN.com's automated news wire. Wire index