Nose tackle Glenn Dorsey sustained a torn left biceps muscle in 49ers practice Friday evening, multiple league sources confirmed to CSNBayArea.com.
Dorsey will continue to be evaluated over the next few days with surgery expected. The length of time he is expected out is yet to be determined, but the injury does jeopardize his season.
Dorsey left the practice field Friday evening during the early portion of the 49ers' workout. A member of the team training staff examined his left biceps while Dorsey flexed his arm during the preliminary examination on the sideline before Dorsey went to the locker room.
The 29-year old is entering the final season of a two-year contract he signed with San Francisco in March of 2013.
In his first season with the 49ers last year, Dorsey recorded two sacks and 30 tackles The fifth overall pick in the 2008 NFL Draft, Dorsey started 13 games after Ian Williams was lost for the season in Week 2.
Williams remains on the physically-unable-to-perform list as he continues his rehabilitation.
Tony Jerod-Eddie, Tank Carradine, Quinton Dial, Mike Purcell and Lawrence Okoye are the only healthy defensive linemen on the 49ers’ 90-man roster.
The injury was first reported by ESPN.