Cowboys linebacker Leighton Vander Esch was injured on Jordan Mason’s 26-yard touchdown run with 13:59 remaining in the fourth quarter.
49ers left tackle Trent Williams blocked Cowboys edge rusher Micah Parsons into Vander Esch, and Vander Esch’s helmet appeared to jam into Parsons side.
He remained down after the play.
Vander Esch did walk off but went directly to the X-ray room.
His history of neck injuries, dating to college, make the injury a scary one for Vander Esch.
The Cowboys list him as questionable to return.
Cowboys cornerback DaRon Bland went to the training room for an IV after cramping up on the sideline.
The 49ers lead 42-10.