I remember learning once that each of the fingers served a different purpose. I don't recall if this was in Talmud or Shulchan Aruch. What do our sources say is the purpose behind each of the different fingers?
Zeret: The pinky finger. In Shemos 39:9 it is used as a measurement, which when doubled, serves as the length and width of the Kohen Gadol’s breastplate.
Kemitza: The ring finger. In the grabbing flour part of a kemitza offering, this was the finger it would start from, spanning to the ama and etzba fingers.
Ama: The middle finger. From the end of this finger to the elbow is the ama measurement for building and vessels.
Etzba: The pointer finger. Used to sprinkle blood of sacrifices on the alter.
Godel: The thumb finger. Used to purify a metzora with blood and oil.