What muscle allows us to play the piano?

Answer 1

While nearly all muscles in the body are used in either an active (depressing a key) or passive (keeping you sitting up straight) way, I assume your question to be more focused on the muscles that specifically act on the fingers and wrist. In that case you have:

The Extensors of the Wrist and Fingers

(pull the wrist and fingers away from the keys)

• Extensor Carpi Radialis Longus
• Extensor Carpi Radialis Brevis
• Extensor Carpi Ulnaris
• Extensor Digitorum
• Extensor Indicis

Flexors of the Wrist and Fingers

(pull the fingers and wrist toward the keys)

• Flexor Carpi Radialis
• Palmaris Longus
• Flexor Carpi Ulnaris
• Flexor Digitorum Superficialis
• Flexor Digitorum Profundus

Short Muscles of the Thumb

• Abductor Pollicis Brevis
• Flexor Pollicis Brevis
• Opponins Pollicis
• adductor pollicis

Lumbricals

Palmar Interossei

Dorsal Interossei

Hypothenar Eminence

• abductor digiti minimi
• flexor digiti minimi brevis
• opponens digiti minimi

That pretty much covers the ones that will be actively used to operate the fingers. There are other muscles that are used, but to a much lesser degree for the action of specifically pressing the keys and orienting the fingers into position to play the individual keys and chords etc.

Sources:

11yrs practical anatomy understanding from Jujitsu

6months of Massage Therapy School

1yr of piano lessons in High School

"Trail Guide to the Body" 4th Edition by Andrew Biel