A couple of years ago, my daughter I were helping a friend show her horses. We were at the warm up pen observing, when a young girl was suddenly in trouble. Her horse began hopping, and for some reason she seemed to think that she was going to dismount by the right side.
Instead she was flipped over the horse, and landed on her head. As I bystander, I ran to her to stabilize her. She landed sitting up. She did indeed break her neck, as was found out later. She has made a full recovery. She was wearing a helmet, and that minimized her having other injuries. Now my daughter becomes very upset if she see's people riding with out helmets.