The body has over 630 muscles, which make up almost half of its total weight.
We all have muscles, even cows, pigs, snakes and worms. Muscles allow us to move our bodies; without them we couldn't jiggle, wiggle, walk, talk, stand up, sit down or play in the mud. They are also responsible for things we do without knowing it like blinking, breathing, our heart beating and moving the food we eat through our digestive system.
Muscles usually work in pairs to produce movement. To straighten your arm, your tricep muscle (on the back of your arm) contracts and your bicep muscle (on top of your arm) relaxes. When you curl your arm, like you are making a muscle, your tricep muscle relaxes and your bicep muscle contracts. Our muscles use energy from the food we eat to make movements.
You have more than 30 muscles in your face. These muscles make you look surprised, happy or sad.
Eye muscles are one of the busiest muscles in your body: scientists believe they move more than 100,000 times a day.
The largest muscle in your body is called the gluteus maximus, which is the muscle in your buttock.