Employment Law Questions? Ask an Employment Lawyer.
Dear Customer, you will want to speak with a worker's compensation lawyer.
The reason you want to talk to a local lawyer in this particular situation is two fold. First, worker's compensation is the sole remedy for workers injured on the job due to negligence, you may be entitled to damages for your injury. Second, the attorney can help you review the documents that your supervisor had you sign and help you decide whether or not it is worth contesting them (it may or may not be, depending on the specific facts of your case - your attorney can help you better understand the risk/benefit analysis in conjunction with all of the facts).
An attorney can do all of this for you with attorney/client privilege (nobody else will know what you are discussing) and they will be able to provide you with a formal legal opinion regarding the matter.
Most worker's compensation attorneys provide free consultations. You can find local attorneys using the State and local Bar Association directories, or private directories such as www.AVVO.com; www.FindLaw.com; or www.Martindale.com (I personally find www.AVVO.com to be the most user friendly).