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)
There's been chatter on the Web, and in YouTube comments, about whether the two guys in this Progressive commercial are supposed to be a couple. The evidence is thin but as best I can tell consists of the following elements: The tall guy's speech and mannerisms seem to be tripping a lot of folks' gaydar.