Guidonian hand
In Medieval music, the Guidonian hand was a mnemonic device used to assist singers in learning to sight-sing. Some form of the device may have been used by Guido of Arezzo, a medieval music theorist who wrote a number of treatises, including one instructing singers in sightreading. The hand occurs in some manuscripts before Guido's time as a tool to find the semitone; it does not have the depicted form until the 12th century. Sigebertus Gemblacensis in 1105–10 did describe Guido using the joints of the hand to aid in teaching his hexachord. The Guidonian hand is closely linked with Guido's new ideas about how to learn music, including the use of hexachords, and the first known Western use of solfege.
Michelangelo Hand
Austrian electrician Patrick Mayrhofer suffered serious injuries to his hands at the age of 20 when he touched a 6000-volt power line in February 2008. After unsuccessful attempts to reconstruct his left hand, it was amputated below the elbow in July 2010 and he became the first patient in the world to be fitted with a Michelangelo Hand. He joined Ottobock 3 years later, helping their customers learn to use their prostheses. Having started para-snowboarding in 2012, Mayrhofer was named Paralympic Austrian Sports Personality of the Year after winning a gold medal in banked slalom at the 2015 Para-Snowboard World Championships He went on to win the Paralympic silver medal in banked slalom at the 2018 Winter Olympics.