I was lubing a motorcycle chain many years ago, and turning the wheel, as I applied the lube, I rolled my index finger into the chain and sprocket. Punched a hole like a crimp on a wire terminal. I then had to roll the wheel backwards to remove my finger. Then it started to gush blood. After x-ray, found out it had chipped the bone. Hurt like he**. It healed up normally.
The same finger had been trimmed by a jointer, in my younger years, after we removed the safety guard to do production work. I was trying to keep the table clean, and swiped my finger across the jointer knives to remove the wood chips. That finger is more pointed than rounded . Safety guards are there for a reason, use them.