There's nothing remarkable to see; I escaped unharmed except for a very few exceedingly superficial scratches. I was fortunate that the brambles were quite young, and hadn't developed particularly large or hard thorns, and had fairly pliant stems. It was actually a good thing that they were there, since the slope I landed on was quite steep, and I might have rolled down it until I hit a tree if the brambles hadn't caught me, and they cushioned the impact too. Landing on the path would have been a lot worse; it was packed with protruding sharp rocks, which is why I tripped in the first place.