The advice to Angie about her accident moved me to post. My horse recently fell with me. He tripped walking downhill on that very hard, cracked adobe California is famous for. I ended up riding him right to the ground, where he rolled onto my left leg, and my right elbow slammed into the ground. I only ended up with bruising and sprains on the left leg, though my right arm is still bothering me. I really came off pretty lightly, all things considered. I've been going over what I could've done differently, and came to the conclusion - not much. If I'd have tried to bail and landed on awkwardly on that hard adobe, I might've broken my back, or something else. Sometimes you just have to pray whatever happens won't be too bad!
(And yes, I read all those posts about tripping horses, and almost posted then - my mare tripped with me about 20 years ago - I hyper-extended my arm trying to keep her up - and ripped a muscle in my back that bothers me to this day. Won't do that anymore!)