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
Numerous American soldiers who suffered limb amputation in combat have received Michelangelo Hands since 2011. In January 2012, Matt Rezink of Wisconsin became the first American civilian to receive a unit. In January 2013, Chris Taylor, a British service engineer who had lost his right hand in a jet ski accident in 2009, became the first UK citizen to be fitted with a Michelangelo Hand. By 2013, the hand was offered by several British prosthetic services companies, including Dorset Orthopaedic.