First Children Encyclopedia

(Marvins-Underground-K-12) #1

107


Muscle magic


Muscles are rubbery,


stretchy straps.


You can control


some of your muscles,


like the muscles in your


arms and legs. Others,


such as your heart and


bladder, operate without


you having to think


about it.


Making faces


Muscles in your face are


attached to skin as well as


bone. They allow you to


make all kinds of expressions


to show how you are feeling.


Bones and muscles


There are 206 bones in an adult skeleton.


Ankles contain different
joints for up-and-down
and side-to-side movement.

Wrists have a joint that
allows them to turn but
not go all the way round.

Neck bones feature a
pivot joint that allows
your head to turn.

Thumbs have joints that
allow them to rotate,
which fingers cannot do.

Bending bits


Different kinds of joints


all over your body keep


you moving.


Pulling pairs
Muscles can pull
but they can’t
push. They work in
pairs that pull in
opposite directions.

Biceps and
triceps bend
and straighten
your arm.

The pectoralis
muscle moves
your arm at the
shoulder.

The biceps
contract to pull
the forearm up.

The tibialis
muscle bends
your foot.

The triceps relax
and stretch when
the biceps contract.
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