(En español: Músculos involuntarios)
Say: in-vah-lun-tair-ee muh-sul
You don't have any say over what this kind of muscle does and when. It just does its thing and works without you even thinking about it! One very important involuntary muscle is your heart, which keeps beating all day and night. Other involuntary muscles help digest food and are found in your stomach and intestines. It takes guts to be an involuntary muscle!