It had to happen sometime, and this weekend was it. Echo spooked left, I went right, and over his shoulder I flew. I landed on my butt, then something smacked me on the back of my head. I'm not sure if it was Echo's foot or the ground - Fuzzypony was there but didn't see the fall. I hung on the the reins for dear life (we were a mile from home), but after being dragged 20 feet, I let go. Fortunately, Echo stopped next to Taran, and we managed to catch him, no harm done. Unless you count the impressive case of road rash on my lower back. Owie.
Adopted Horse Mom never, EVER let me get on a horse without a helmet or gloves. I actually feel naked without them. Of course if you're on a green horse, you're pretty likely to wear a helmet. Whatever I hit my head on, I hit it HARD. Like replace-my-brand-new-helmet hard. I was lucky and walked away with a mild headache. I didn't lose consciousness, wasn't nauseous, or anything like that. If I hadn't been wearing that helmet, I am quite sure I would not have walked away from that fall.
But you know what, my falling off was not Echo's fault. He spooked sideways at he goats at the end of the arena. And frankly, it was the sort of spook I should have been able to sit. Besides, he had just bravely walked past a couple of mountain bikers on the trail without batting an eyelash. You just never, ever know.
Wear your helmets, y'all. Every ride, every time. Just do it.