Self-Inflicted Wounds.

[magical thyme]

14. that's where his claim of being banged repeatedly on the cement falls apart

I don't doubt the blood on his head or his bloody nose at this point. The police records indicate the bleeding, and the EMT report states that there were minor injuries.

Pure speculation: Trayvon punched him in the nose and he fell down and hit his head on the edge of the paved walkway between the townhouses. Hence the horizontal cuts across the back of his head. Then he got really pissed off that that n-boy getting the better of him, and pulled out his gun.