Others, like the muscular contracting of your heart, the movement of your diaphragm so that you can breathe, or blinking your eyes are automatic. They're called involuntary movements. Through signals from your nerves, and, in some cases, your brain, as well. And, like these other living body parts, with a little help, they generally mend themselves. You have over 30 facial muscles which create looks like surprise, happiness, sadness, and frowning.
Eye muscles are the busiest muscles in the body.
The largest muscle in the body is the gluteus maximus muscle in the buttocks.