evidence: First, let’s start with what a Stroke or Cerebroventricular Accident (CVA) is so we have better understanding of why, "Stick Out Your Tongue" helps identify a stroke victim. [...] So how does "Stick Out Your Tongue" help evaluate if a person is experiencing a possible stroke? Well, the tongue is actually controlled by both sides of the brain through the hypoglossal nerve which controls the intrinsic musculature of the tongue determining movement of the tongue, lateral or side to side movement. [...] So, if you suspect a friend, family member, or coworker is experiencing a stroke, ask them "stick out your tongue". What you’re looking for is that the tongue will appear crooked (curved toward one side of the mouth or the other), or appear a bit twisted, while the other side of the tongue will appear flat (normal) and smooth.