EE WAS OPERATING A 777 CATERPILLAR ROCK TRUCK AND WHILE BEING LOADED, A PIECE OF ROCK FROM THE LOADER BUCKET FELL ON THE TRUCK BED. THIS BOUNCED THE EE. EE STATED THAT HE FELT A PAIN IN HIS NECK AND ARM. AS OF 5/24/04, EE IS WAITING ON RESULTS OF MRI EXAM.