The nurse caduceus is the symbol of the U.S. Army Nursing Corps.
This emblem used by the U.S. Army medical department is comprised of the staff of Hermes. This is a winged staff with two serpents intertwined about the staff in a double helix pattern.
Historically the actual symbol of physicians and healers was the rod of Asclepius which is a rod without wings and a single snake coiled around the rod. This symbol has been adopted by the American Medical Association as their official symbol.
The Caduceus was adopted in 1902 as the result of a case of mistaken symbols on the part of a medical officer in the Army Medical Corps. The mistaken identity has caused some confusion and historically many admit that symbolically and historically it would be more appropriate to use the rod of Asclepius as many civilian practitioners do. Military Heraldry can be difficult to change once it has been adopted .
The Nurse Corps emblem is comprised of the winged rod with twined snakes and an embossed N located just below the wings of the emblem. The Army Medical Department or AMEDD has codified this symbol for a variety of professions in the medical arena of the Army. Each major corps is represented by the caduceus with an embossed letter. D for dental, V for Veterinary, S for medical specialists, MSC stands for Medical Service Corps and the emblem without a capital letter is representative of the medical corps.
The staff of Hermes is also called the heralds staff. It is considered a symbol for messengers. Hermes was also considered to be the god who dealt with the passage of the dead to the other side. The rod of Hermes was also adopted by the Romans but Hermes became Mercury. The Romans considered Mercury to be the god, who in addition to helping souls cross over to the land of the dead, was the protector of merchants, thieves and gamblers as well as liars.
The association with serpents is one that dates back to the Greeks who considered medicines to be both beneficial and poisonous. Serpent venom was considered to have healing or curative properties.