He mistakenly believed that thinking took place in the heart and that the brain functioned like a radiator, cooling the blood. Today, of course, we know better. Without a brain, you or I would be worse off than the scarecrow in The Wizard of Oz. The brain is the command center, connected to every part of the body through a complex nerve system. When something goes wrong with the connections, either through breakage or through a chemical abnormality, the results are apparent.
Paralysis occurs when the spinal cord is severed.
Other times the symptoms may be a varying degree of loss of muscle control, or a problem with speaking. No, this isn't a chapter out of a basic human anatomy textbook. I'm just trying to make a point. Although the brain may be perfect, the body will not respond perfectly if the connections are faulty. Jesus is described as the Head of the Body.