Aglahad -- this is off topic, but I was looking at the Branch Insignia. When I got to all the medical/nurse, I looked up where the pole with wings and two snakes came from... for Nurse Corps, as an example, here is the writeup:
http://www.tioh.hqda.pentagon.mil/UniformedServices/Branches/Army_Medical.aspx from
https://netfiles.uiuc.edu/ro/www/armyrotc/branches.pdf
So, not knowing where the "caduceus" -- the pole with wings/snakes -- came from, I looked that up in wikipedia.
http://en.wikipedia.org/wiki/Caduceus It actually says there that the caduceus is NOT a medical symbol at all, and that it has been mis-applied in the US to refer to medically related fields. It goes on to say the correct symbol for medical services is a pole with a single snake and no wings --,
"The caduceus is sometimes mistakenly used as a symbol of medicine and/or medical practice, especially in North America, because of widespread confusion with the traditional medical symbol, the rod of Asclepius, which has only a single snake and no wings."
So I looked up the rod of Asclepius, and sure enough it is a rod without wings, and a single, not double serpent, that is supposed to relate to the medical fields.
Not that this makes any difference, but I found it interesting that somewhere way back in US history the wrong historical symbol was adopted my medical colleges, or whomever first used it, and then by the Army, to refer to the medical arts.