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)
Let me get one thing straight immediately. Progressive's 100th ad featuring Flo does not merit four stars all by its lonesome. In fact, as a stand-alone ad it almost fails entirely. Sure, it's funny in an Eddie Murphy or Mel Brooks or Martin Lawrence sort of way.