I have nearly knocked myself out on concrete when falling backwards with NO tear of skin.
Ten minutes later in class I started getting dizzy and dissoriented. They sent me to the nurse. I laid down for about an hour and fortunately I was fine. There were no lacerations whatsoever.
This story does explain a lot about my posting style, however...
OMG. I think that was me that pulled the chair out......lol. Sadly, I did that to someone in school, felt terrible.
I came off a horse and landed back first on a rock. My noggin hit the concrete hard ground of the southern Arizona desert. My back was bruised severely. My noggin was not. But it was several hours before I could think clearly.