I have three memorable falls.
The first was in high school. I was running down a steep single-track trail and my toe caught a boulder. I went airborne, landing facedown. It happened so fast that I was hitting the ground by the time I realized I had tripped. No time to brace myself at all. I landed hard and got the wind knocked out of me. I was bleeding all over (side, hip, forearms, wrists, hands). The scary part is that I was probably 1 1/2 miles from the nearest road and it was a weekday morning. I thought I might be lying out there for hours. Luckily I got my breath back and walked/limped back to my car.
Second time was in college. There was snow on the ground and I was coming up on a small stream. The snow covered the stream, so I decided to run right over it. I didn't realize how thin the snow was on top of the ice. With my first bound onto the stream, my foot shot out from under me. I went down hard on my back. Again, the wind got knocked out of me. I was about 2 1/2 miles into a 9 mile run. I'm pretty sure I ended up jogging slowly the rest of the way.
The most recent time was last summer. I was going at a pretty good clip (probably 6:15 to 6:30 pace) when my toe caught a root. I was in the process of putting my arms out when I hit the ground. My elbow jammed into my ribcage. I ended up bruising a rib. It hurt to breathe, cough, laugh, etc. for three weeks. It was miserable.