All our movements depend on our amazing muscles. In this lively volume, readers will discover how the three kinds of muscles, skeletal, cardiac, and smooth, work in collaboration with their other body parts to keep them moving. They'll learn what extraordinary machines the human body's more than 600 muscles are as well as how to keep them healthy and toned. Accessible text and supporting diagrams and photographs make this book a valuable tool in addressing an important topic of the elementary science curriculum.