The worst thing you can do at a crash scene is ask the hurt person how they feel and write down the answer.
The first move
The instant of a crash, the nervous system does not stop to take inventory. It floods with adrenaline, shunts blood to the big muscles, and gets the body ready to move, to run or fight or lift a car off a child. This is fight or flight, and it is built for the next five seconds, not the next five hours.
Why nothing hurts yet
In that flood, the body turns its own pain down. Under acute stress the brain releases its own opioids and blocks the signals climbing up from the injury. The soldier who runs on a broken leg and the driver who climbs out and says "I'm fine" are the same machine doing the same thing. The pain has not arrived. It is being held back.
When it arrives
Hours later the adrenaline drains, the body's own painkillers wear off, and the inflammation from torn tissue is just getting started. That is when the neck locks, the back seizes, the headache sets in. The person who felt fine at the scene wakes up unable to turn their head. Nothing new happened. The injury was always there. The body was too busy surviving to feel it.
The freeze
And some people do not run or fight. They go still and silent, unable to move even to protect themselves. Tonic immobility is involuntary and well documented, and it is not weakness and it is not consent. It is one more setting on a system nobody gets to choose.
The lesson
"I'm fine" at the scene is physiology, not a diagnosis. The record made in the first hour, the recorded statement, the refused ambulance, is a record of a body flooded with its own anesthetic. Read it that way, and get the client to a doctor before the adrenaline lies for them.
On the body's suppression of pain under stress, see stress-induced analgesia and the endogenous opioid system (PMC). This is general information, not medical or legal advice.
