Myelinated nerve fibers occur predominantly in the cranial and spinal nerves and compose the white matter of the brain and spinal cord. It is the myelin sheath that gives the whitish color to the areas of white matter. Unmyelinated fibers are abundant in the autonomic nervous system. Patient discussion about myelin
The actress in the Progressive Insurance commercial is Stephanie Courtney. Her commercial name is Flo. Other roles in which Stephanie Courtney has appeared: Mad Men (Marge, a secretary) Blades of Glory (reporter) The Brothers Solomon (Sara)
Here's The Evidence That Progressive Is About To Kill Off Flo. In adland, it's been stated so often it's now a truism: America loves Flo, the Progressive insurance pitchwoman played by comedian Stephanie Courtney, and a huge portion of the company's brand equity is tied up in the Flo character.