In some states, you have a right to see your own doctor if you make this request in writing before the injury occurs. More typically, however, injured workers are referred to a doctor recruited and paid for by their employers.
Your doctor's report will have a big impact upon the benefits you receive. Keep in mind that a doctor paid for by your employer's insurance company is not your friend. The desire to get future business from your employer or the insurance company may motivate a doctor to minimize the seriousness of your injury or to identify it as a preexisting condition. For example, if you injure your back and the doctor asks you if you have ever had back problems before, it would be unwise to treat the doctor to a 20-year history of every time you suffered a minor pain or ache. Just say "no" unless you really have suffered a significant previous injury or chronic condition.