Can a pinched spinal cord in the neck cause muscle weakness and astrophy on your whole arm and leg muscle. can a pinch back spinal cause same.

Yes to both : That pinch or narrowing of the spinal canal causes you to have pain. Pain when you move it is a signal that if you don't move it it will not hurt. Lack of use will cause that muscle to thin or atrophy. Best find out what's going on and take care of it

Yes, and yes: If you are experiencing these symptoms, you need to see your primary clinician and likely a neurosurgeon to fully evaluate and treat. If there is muscle weakness, you need to move quickly because you might permanent lose function.

To involve the leg: there would have to be spinal cord involvement or a second lesion below the cervical level. If you develop increased tone and reflexes to go along with weakness and atrophy the problem may be further upstream (eg stroke). If the issue is "where is the lesion ?" the answer may need to come from a neurologist. That's a big part of what we do.