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Cells are the building blocks of life These are skeletal muscle cells CONTENTS YOUR AMAZING BONES AND MUSCLES 4 AN ENGINEERING MIRACLE THE STAGGERING SPINE g muscle cell 10 BODY ARMOR 12 BEND DON T BREAK 14 BONES FOR TRICKY JOBS 16 MARVELOUS MUSCLES muscle tissue MUSCLE POWER 20 MUSCLES OUT OF CONTROL Muscle cells join 22 together in FACING FACTS 24 BREAKING BONES strands called fibers The fibers join together to form muscle tissue 26 TEARS AND STRAINS MAINTENANCE AND SERVICING Muscle tissue can form muscles organs such as those in your arms BONE AND MUSCLE WORDS and legs FOOD FOR BONES AND MUSCLES 31 32 INDEX Your muscles work together to form your musculoskeletal system This includes your bones and muscles organs that help you move
NE AMAZING BONES BRILLIANT BODY FACT AND MUSCLES The hyoid bone in your throat is the only bone that doesn't connect with any other bone What's the reason you aren't blobbing around on the floor like a jellyfish right now Your BONES They provide a structure for your body snail shell like a's or a suit of armor but on the inside Your bones and muscles COOK CLOSER SKULL PLATES give your body its shape infant skull Joining together As a baby you had over 300 bones but as you grew some of them fused together For example your skull starts off as eight soft bony plates with gaps between them There are good things spaces between bone plates and bad things about this arrangement Good things It allows a baby's skull adult skull to compress in the narrow birth canal after you're born it also lets your skull expand as your brain grows Bad things A flexible skull doesn't provide very much brain
Soon after you were born the bones in your skull DID YOU KNOW started to join together By the time you were about 18 months old your skull had become a strong Without bones you couldn't speak helmet under your skin As you grow bones fuse in some other parts of the body too By the time you reach adulthood your 300 bones have become just 206 Humans have a little bone called a hyoid in their throats It works with the voice box and tongue and makes speech possible The hyoid bone acts as an anchor for the tongue attaching it to the throat at one end This gives the te wide range of movement Muscle magic Of course bones alone can't do much To stand up straight sit and lie down you also need muscles These work like tug of war teams pulling your bones back and forth as instructed by your brain The jaw muscle is very strong You use it for everything from laughing to eating hyoid b Jone g See for yourself Test your muscle movement Hold your arm out straight with your palm up Put your other hand on top between the elbow and shoulder It's now resting on your biceps muscle Next bend your arm so that your fingertips touch your shoulder The biceps muscle went from long to bunched up as it pulled your arn into a bent shape Bones are connected by joints Muscles pull the banes on either side of the joints which is what makes activities such as running
