Sensory Motor Amnesia--a term coined by Thomas Hanna, in which muscles have become habitually contracted (tight), as a reflex to stress, trauma, etc, and neurologically one's brain must be retrained to relax said muscles.
Let's Go Deeper
Hanna equated SMA to the the same process of learning any skill. Your muscles respond to an accident, trauma, injury or just plain old day-to-day-hunching-over-your-desk stress by contracting. Over time your muscles repeatedly contract in response to the stress or pain, so that eventually it's an unconscious habit.
Maybe you're unaware that your shoulders are constantly elevated towards your ears or that you're still hiking your hip due to a sprained ankle that "healed" five years ago. All you know is that now you have aches and pains, maybe even in other parts of your body, that no amount of stretching, massaging, chiropractic adjusting will fix long term.
Your brain and body have developed sensory motor amnesia. But in the same light that your muscles have created a faulty pattern, you can tune into your body's imbalances, practice Somatics exercises, and retrain your brain to relax your muscles, so you reverse your pain and regain a more supple body.
It's so simple yet so profound. If you'd like to experience it for yourself let me know. I offer somatic exercise classes and private sessions. I love it and I bet you will too!