What part of the brain is used to play the violin

It's the (cortex). The cortex is the developed part of the brain the allows the outer layer of the brain the allows a human to play the violen.  There's two parts of the brin the allows one to play a violen.

Humans can learn to play music because of their highly developed cortex. Cortex actually means “bark” and it's the outer layer of the brain. In a way, you could also say musicians use both the outer and inner parts of their brains, too. As musicians play an instrument, the cortex helps them learn and understand.