How Muscles Work

By Holly Homer


One of the most magical things about life is how our bodies move. It is an amazing and complex system of bones, nerves, ligaments and muscles that is controlled by the brain. The brain is so good at controlling these things that often we don’t even have to think about moving!


How Muscles Work

An easy way to look at what happens in the body is to build a simple joint out of Tinker Toys. Create a triangle from two wooden pieces, a hinge and a rubber band or an uninflated long balloon.


Each of these pieces has a role to play:

  • Bones: The wooden sticks are bones. Bones are solid and strong. They don’t bend or change form.
  • Joint: The hinge is playing the part of a joint in the body. There are simple joints that work similarly to this hinge. You can find them in fingers and toes and the part of the elbow that is closest to the body.
  • Muscle: The stretchy part of this triangle is the muscle. Muscles can get longer or shorter to move the joint.


Making Bones Move

Since bones can’t move or bend by themselves, muscles do all the work. Muscles are attached to bones. Where they are attached to the bone determines what type of joint movement they will create.

  • Flexion (or bending of the joint) is when a muscle gets shorter (like when you let the rubber band pull the sticks together).
  • Extension (or straightening of the joint) is when a muscle gets longer (like when you stretch the rubber band while moving the ends apart).


Muscle Team Work

There are about 642 muscles in the body. Some are very small, and some are quite large. Each movement that we do is a muscle team action. Each muscle has its job to do to help. Some muscles hold a joint steady while other muscles make the movements. That is why even sitting still uses muscle strength!


Compensation was provided by Sylvan Learning. The opinions expressed herein are those of the author and are not indicative of the opinions or positions of Sylvan.