Answer:
Muscles in our hands (skeletal muscle) are called voluntary, because these muscles act according to the impulses (orders) given by our conscious brain.
Heart (cardiac muscle) is an example of an involuntary muscle. It works all the time with impulses from our brain stem, which is involuntary.
some more examples of voluntary muscles in our body are, muscles of the chest, neck, abdomen, etc. and those of involuntary muscles are, muscles of the digestive system, smooth muscles etc.