Cannon, who is one of San Francisco’s primary special teams players, was chasing down Seahawks returner DeeJay Dallas when he collided with 49ers safety Talanoa Hufanga. On the play, Cannon attempted to tackle Dallas from one side as Hufanga converged from the other.
Both Cannon and Hufanga missed Dallas, and Hufanga’s left thigh hit Cannon in the head as his neck bent backward. Cannon stayed on the field for minutes as medical personnel tended to him. After bracing Cannon’s neck, medical officials removed his face mask, and he was loaded on to an ambulance and taken off for further observation.
Soon after, Cannon was ruled out for the rest of the game with a concussion.