MUCKING OUT ROUND @ 46E-5900 OBSERVED REBAR IN FRONT OF MUCKER. DRIVER OPERATOR PARKED MUCKER, WALKED IN FRONT OF TO REMOVE REBAR. WHILE BENDING OVER TO REMOVE STRUCK IN BACK OF HEAD BY ROCK, UNKNWON SIZE. DRIVERY OPERATOR WITH APPROX. 1"" LACERATION TO BACK OF HEAD.