EE was hanging fly (back-up) pads in NO. 4 entry. He was driving a nail with his hammer; he felt pain in his right wrist. He did not hit his hand or wrist or strike it against anything but that it just started hurting. His wrist continued to bother him and he was seen by a physician on August 9th and was diagnosed with a sprained right wrist and a cast was applied to immobilize it.