Study shows that the brain processes chronic pain and acute pain differently, and different types of pain (back pain vs Fibromyalgia for ex.) are processed differently as well as shown in fMRIs: could lead to targeted therapies.
What many people don't understand is that pain itself can cause harmful side effects and can affect concentration and mental clarity just as profoundly as any drug. Scott Strassels, College of Pharmacy
This is a diagram of the trigeminal nerve, all three branches. some people are only affected in part of the nerve, one branch or even just part of a branch. I was "lucky" enough to have pain in all three branches as of this time.