Ask for an incident report to be written up. I cannot stress to you how important that is. That's simply just documents about the injury.
I've had cases in the past where the injured worker did in fact report the injury to the supervisor immediately. However, because an incident report wasn't written up or filed, the insurance company was not made aware of the injury in the beginning. So what that does is delay your treatment. It delays the income benefits and the medical treatment that you're due.
So ask for an incident report to be filed, then ask for a copy because you are due a copy of that report. Not a lot of employers will give you a copy if you choose not to ask for it to be filed within your records. That way, when your attorney is on the record, he or she can go ahead and request a copy of your entire employment record - which would include that work injury claim form.