An employee was unloading pallets of product from a trailer when a plastic-wrapped pallet became stuck against the bulkhead of the trailer. The employee was dislodging the pallet when he lost his grip and fell backward, striking his head on the side of the trailer. He then tripped over the forks of a pallet jack and fell to the floor of the trailer. The employee was hospitalized with a brain bleed and pain in his lower back and ribs.