[marcia s. freeman] how muscles and bones hold you(bookfi.org)

7/28/2019 [Marcia S. Freeman] How Muscles and Bones Hold You(BookFi.org)

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Table of Contents

Our Skeleton 4

A Replica Model 8

Joints 10

Muscles and Tendons Let Us Move 14

A Representative Model 18Glossary 23

Index 24


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Our Skeleton

Have you ever seen the wooden framework

of a house? Our body has a framework, too. It

is made of bones.


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But unlike a wooden frame, our bones are

not nailed or bolted together. Ligaments,

muscles, and tendons hold our bones together.


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Ligaments attach one bone to another.

Ligaments are like pieces of stiff elastic that

can stretch a little when the bones move.

SkullMuscle

Ligament


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Bone

Muscle

Ligament


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How can we learn what our bones, muscles,

tendons, and ligaments look like and do? One

way is to study a model. A model represents

things that are difficult to see or measure.

A Replica Model


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A plastic model of our skeleton shows how

our bones are arranged. It is a replica of our

framework.


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Bones are connected at joints. Some joints

are like door hinges.

Joints


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Some joints have a ball and socket

arrangement. Ball and socket joints let us

move our legs and arms forward and back, or

in a big circle.

Ball

Socket


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The bones in our backthe vertebrae

are stacked with a soft cushion-like disc

between each bone. This arrangement lets

us twist and bend.


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Ligaments hold our bones together, but

muscles make our bones move.

Muscles and Tendons

Let Us Move


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Without the work of our muscles we would

be just a pile of bones in a bag of skin.


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Muscles are attached to our bones by

tendons. If you eat a chicken leg, you can see

tendons and muscles.

Notice how the leg musclethe meat

ends in a whitish rubbery band. That is thetendon that attaches the leg muscle to the

leg bone.


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A Representative Model

How do muscles move our bones? We can

construct a model to show how our muscles

and bones work together.


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This model of an elbow shows how our arm

bends. It shows how we can lift something. It is arepresentational model.

Biceps Muscle

Elbow


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Squeezing a balloon represents what

happens when you contract (flex) your

biceps muscle.


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Now relax your arm and notice what

happens to your muscle.


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Models help us figure out what things look

like and how things work.


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Glossary

biceps (BY ceps) one of the main muscles of theupper arm

disc (disk) a flat, round object

hinges (hinjz) jointed or flexible devices that

allow the turning of a part, such as a door or lid

socket (SOK it) a hollow into which a part fits

replica (REP le kuh) a copy or reproduction


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Index

biceps 20

flex 20joints 10, 11

ligaments 5, 6, 7, 8, 14

model 8, 9, 18, 19, 22

tendons 5, 8, 14, 17

vertebrae 13

Further ReadingSeuling, Barbara.From Hand to Toe. Holiday House, 2002.

Arnold, Caroline. The Skeletal System. Lerner Publications, 2005.

Johnson, Rebecca L. The Muscular System. Lerner Publications, 2005.

Websites to Visitwww.rad.washington.edu/radanat/elbow

www.surfnetkids.com/human.htm

kidshealth.org/kid/ill_injure/aches/broken_bones.html

About the AuthorMarcia S. Freeman loves writing nonfiction for children. Her fifty or

more childrens books include science, geography, and math titles. ACornell University graduate, she has taught science and writing to

children and their teachers from kindergarten through high school.

[marcia s. freeman] how muscles and bones hold you(bookfi.org)

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