Activates pain-modulating systems in the brain that project to the spinal cord. Could be placebo effect. Back pain, minor surgical operations Placebo Reduces anxiety. Could be placebo effect. Football player continues to play regardless of injury.
Soldier continues to fight regardless of wounds.
The brain itself does not have any receptors for pain. In fact, most brain surgery is performed using a local anesthetic only. The National Headache Foundation and National Institute of Neurological Disorders and Stroke also have more information about the causes of headache.