Pins and Needles in Hands and Feet - Causes, symptoms and treatment

“It's not critical because there's blood getting through, but if it happens for long enough, what happens is that the blood supply to the nerves at the end of your arm gets cut off. "Then the nerves start to fire to warn us that this is happening, and that we need to do something about it because the blood supply's cut off. “So the nerves firing is what causes that funny pins and needles sensation that we all know about.”