The senior took what appeared to be a legal hit along the sideline after scrambling for a first down in the second quarter of the crucial Big Ten matchup. But on the way to the ground his helmet violently collided with the turf.
After being evaluated for more than 10 minutes, having his helmet, jersey and pads removed by attending personnel and then being strapped to a backboard, Armstrong was carted to a waiting ambulance behind the south endzone and taken from the stadium.
Armstrong was able to give a thumbs-up sign with his left hand after being placed on the cart. He left the field to chants of "Tommy" from the crowd
According to Nebraska medical personnel, Armstrong was briefly knocked unconscious. He was moving all extremities and talking while on the field and was taken to a local hospital for further evaluation.
He eventually returned to the Horseshoe still wearing pants from the hospital after an additional examination. After changing into a black tracksuit, Armstrong came down the tunnel from the locker room, jogged across the field and was hugged by teammates on the sideline.
Ryker Fyfe came on in relief for the all-time leader in passing yardage in Nebraska history.