How Are Muscles and Bones Related?

Lesson Plan - Get It!

Audio:

Hinges help us move through our environment easily, opening and closing doors with little effort.

We have hinges in our body, called, "joints"! Joints exist anywhere that two bones meet in the human body. Examples of important joints include knees, elbows, and wrists.

Joints allow the skeletal and muscular system to work together for human movement and growth. Read on to learn more about the types of joints in the human body!

Before moving on, if you missed or need to review the previous Related Lessons in this Muscular-Skeletal System series, you can find them in the right-hand sidebar.

Immovable joints do not move, but do contain connective tissues that link edges of bones. We have immovable joints in our skull and jaw. These are the joints that hold our teeth in the jaw!

Some joints move a little, and these are called "partially moveable," or "cartilaginous," joints. These joints attach bones with cartilage. Cartilage is a tough, flexible connective tissue. It is found in joints and the top of your ear! An example of a partially moveable joint is the spine. Each vertebrate in the spine is connected by cartilage, which allows some movement in relation to other vertebrae. This structure prevents the spine from moving too freely, protecting it from injury.

Some joints move freely, like our ankles. These joints are called "freely movable," or "synovial," joints. They are able to move in a variety of directions, depending on the location in the body. Freely moveable joints are called "synovial" joints because these joints contain synovial fluid, that acts as a lubricant for bone movement.

As we have discussed, synovial joints can move in different ways. Learn more about the three types of synovial joints.

Hinge joints move in one direction. Think about how your knee or fingers move, only back and forth. These are hinge joints.

Pivot joints rotate or twist. Do a quick neck circle to demonstrate how your neck moves in a rotating motion.

Ball and socket joints allow for free movement in many directions. Your hips and shoulders are examples of ball and socket joints. Look at the x-ray — can you spot the ball and socket part of the shoulder joint?

These types of joints both promote and restrict movement. They allow free movement in different directions based on the structure of the joint. Bones and muscles determine the structure of joints. Bones provide the support, while muscles provide the flexibility — without either component, joints would not work!

Discuss what you have learned about joints with a parent or teacher before moving to the Got It? section, where you will learn more about the types of joints through interactives and a foldable!