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Keep it moving!
INSPIRING STUDENTS TO LEARN
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Your musculoskeletal
system: Keep it moving!
Y
ou know that your
nervous system controls
your thinking and reason-
ing, and that your circulatory
system keeps your heart pumping.
But what keeps your whole body
moving? From simply standing upright
to running in gym class, it’s your
musculoskeletal system that puts
every part of your body in motion.
The musculoskeletal system is
made up of three components:
bones, joints and muscles. These
groups work together at all times
to help you stay strong and active.
Let’s take a closer look at each
of these important players.
Bones provide
structure and
protection
Not only do our 206 bones give our bodies
shape, but they also protect us from harm.
For example, your skull protects your brain,
and your ribs protect your heart and lungs.
Think about all of the important functions
these organs have while they are
protected by your bones.
Humans start out with more than 300 bones
at birth; as we grow, some of these smaller
bones join (fuse) together to make larger
bones. Around age 25, our bones stop
growing, and we end up with 206 of them.
Skull
Clavicle
Maxilla
Mandible
Vertebrae
Scapula
Humerus
Ribs
Vertebrae
Pelvis
Radius
Sacrum
Ulna
Carpal
Phalanges
Femur
Patella
Your bones grow
as you grow. The av
erage
female’s bones grow
until
she is about 16 yea
rs old;
the average male’s
bones
stop growing whe
n
he reaches 18.
Tibia
Fibula
Tarsals
Metatarsals
Phalanges
It’s easy to take care of your bones. Many sports,
including bicycling and snowboarding, have protective
equipment such as helmets, knee pads and elbow pads.
But there’s more you can do than just wear
protective gear. Exercising builds bone
strength and helps to prevent bone
diseases such as osteoporosis and
arthritis. Calcium also builds bones
and keeps them strong. Calcium is found
in dairy products as well as many green vegetables.
Vitamin D, found in calcium-rich foods and in
sunlight, helps your body absorb calcium.
Protect
your bo
nes
Activity
ones do
How many bhave?
animals
mber
al with the nu
Match the anim
ink it has.
of bones you th
nes
Number of bo
Animal
Cat
Chicken
Cow
Dog
Human
Pig
320
216
206
307
244
207
ls
at most anima
Did you know th
lled
ca
re
a
bones? These
s,
m
don’t have any
or
w
amples include
Ex
s.
te
ra
eb
rt
her
ve
ot
in
Can you think of
.
sh
fi
lly
je
nd
a
spiders
rtebrae?
ight not have ve
animals that m
Take good care of your bones by staying
active and eating healthfully, and your
bones will take care of you!
What are bones made of?
When a bone breaks, our body immediately
begins the healing process by developing tissue.
The tissue starts out soft and gradually turns to hard
bone. A cast protects the growing bone from
risk of further injury.
Articular
cartilage
Articular
cartilage
Spongy
bone bone
Spongy
Compact
bone bone
Compact
Endosteum
Endosteum
Periosteum
Periosteum
Blood Blood
vesselsvessels
Articular
cartilage
Articular
cartilage
What
are
bones
made
of?
The outer layer
is called
the periosteum.
This thin
The outer
is called
theblood
periosteum.
Thisprovide
thin
layer
holdslayer
the nerves
and
vessels that
layer
holds
the
nerves
and
blood
vessels
that
provide
nutrients to your bones.
nutrients to your bones.
The middle layer is made up of two parts: compact
The middle
layer bone.
is made
upcompact
of two parts:
bone
and spongy
The
bone is hard
compact
bone
and
spongy
bone.
The
compact
and smooth, while the spongy bone is squishy bone
like
hard andThese
smooth,
spongy
bonetoismake
squishy
aissponge.
twowhile
layersthe
work
together
like abones
sponge.
These
layers work together to
your
strong
yettwo
light.
make your bones strong yet light.
The innermost layer is called the marrow, or
The innermost
layer
is called
or
endosteum.
This
contains
the the
cellsmarrow,
that produce
endosteum.
This
contains
the
cells
that
produce
blood, fat, cartilage and bone.
blood, fat, cartilage and bone.
Activity
Make a
Bone-Healthy
Smoothie
Mix together in a blender
1 cup blueberries,
1/2 cup nonfat milk,
half of a medium banana,
1/2 cup vanilla yogurt,
1 cup spinach
1/2 tablespoon honey.
Blend until smooth.
Answers: Cat 244, Ch
6,
Dog 320, Human 20
icken 307, Cow 207,
Pig 216
Joints and cartilage and ligaments:
Keeping your bodies in motion!
J
The
in your
bone
oints are the places in your body where bones connect.
Without them, we wouldn’t be able to move. In both of your hands and wrists alone, you have about 80 joints.
Cartilage protects your bones at the joints, preventing them
from rubbing against each other. Cartilage is a slippery substance that can soak up and push out water like a sponge.
It’s ideal for joints, because it can absorb shocks.
Think about the stress that running puts on your knees
Cartilage helps take the pressure off your joints.
It also lubricates joints and allows them to move
smoothly. When you’re running, for example,
your joints move in a seamless motion.
Even when you’re not physically active, your
cartilage is still working. While you are seated,
cartilage stores the knee’s joint fluid. When you
get up, the fluid squeezes out of the cartilage and
into the joint. This lubrication and cushion is
what makes it possible to stand up or run.
Ligaments, made up of strong bundles of
elastic fiber, reinforce your joints and
help guard against dislocation. They
tighten when your joints are stressed,
and release when they’re at rest.
Whether you’re playing hard on
the basketball court or just
waving to a friend, all of
these parts work together.
he
half of t are
n
a
h
t
e
r
y
Mo
man bod
u
h
e
h
t
n
et
bones i
s and fe
d
n
a
h
e
in th
The longest and strongest bone in the body is your
s
t
n
i
o
j
f
o
s
e
p
Ty
ly movable
ts: fixed, slight
in
jo
of
s
pe
ty
ull, are
main
those in your sk
There are three
as
ch
su
,
ts
in
bones move.
able. Fixed jo
le; none of the
and freely mov
ab
ov
m
im
d
an
locked in place
movable
ples of slightly
am
ex
e
ar
e
in
ints
sp
eely movable jo
rtebrae of your
fr
ve
as
e
h
th
uc
in
m
ts
as
in
not
The jo
able joints
ove a little, but
s). Slightly mov
w
bo
joints.These m
el
or
s
ee
rtilage.
found in your kn
r by pads of ca
he
ot
ch
ea
to
d
(such as those
are connecte
e also called
ovable; these ar
m
e
or
m
e
ar
al joints.
ts in your body
types of synovi
x
si
e
ar
re
he
Most of the join
T
.
synovial joints
e the
d shoulders, ar
an
ps
hi
ur
yo
d in
e of motion
et joints, foun
t the wide rang
ou
Ball and sock
ab
nk
hi
T
t.
t in your
type of join
. Since the join
dy
bo
ur
most movable
yo
of
joint.
e parts
most moveable
ur
you have in thes
yo
is
er
ld
loose, the shou
shoulder is so
rocking from
extension and
g,
in
nd
be
w
lo
the base of
ts al
ed. The joint at
Ellipsoidal join
it
m
li
is
e
ng
ra
dal joint.
t the
e of an ellipsoi
side to side, bu
pl
am
ex
an
is
er
your index fing
elbows.
your knees and
in
d
un
fo
e
ar
of a
Hinge joints
ing and closing
en
op
e
th
ke
li
erate
e direction.
These joints op
tend in only on
ex
d
an
ex
fl
n
door; they ca
und bedeways, are fo
si
y
tl
os
m
e
ov
ts.
, which m
ther by ligamen
ge
to
ld
Gliding joints
he
s
ne
iding joints.
es of two flat bo
examples of gl
e
tween the surfac
ar
es
kl
an
d
Your wrists an
ck.
found in your ne
is
t
in
jo
t
o
iv
The p
to side.
twist from side
It can turn and
ent
greater movem
s
ha
t
in
jo
le
d
joint
The sad
int or a gliding
than a hinge jo
s movement in
because it allow
of
The only type
two directions.
your body
saddle joint in
bs.
is in your thum
r femur. This is the bone from your hip to your knee.
How to protect and strengthen your joints
smallest bone
p
body is the stirru
r.
e inside your ea
The steps you take
to protect your bones
will also protect your
joints. There’s more
you can do to keep
your joints working smoothly.
For example,
aerobic
exercise
(also called
cardiovascular exercise)
such as swimming and biking
take the stress
off of your
joints.
Strength
training also helps.
By strengthening
the muscles around your joints, you are
protecting your joints from harm. Light
handheld weights or resistance bands
strengthen muscles in ways that aerobic
exercise doesn’t.
Building flexibility is important for
your joint health, too. Try some simple
stretching exercises or yoga. Remember
that like any physical activity, it’s
important to warm up before you begin
even a mild workout. Finally, remember
to stand up straight. Maintaining good
posture protects joints in your neck,
back, hips and knees.
What ‘double jointed’ really means
The term “double jointed” is used to describe people
who have a larger range of motion than a joint can
typically perform. For example: You know that your
elbow can move back and forth, but some people are
able to extend their arms beyond what is considered a
normal extension. The scientific term is joint hypermobility, but we might call those people double jointed.
How come some people have this while others don’t?
It mostly has to do with genetics, so don’t push your
joints beyond what they are naturally able to do. In
fact, there are some dangers associated with hypermobility, including an increased risk for arthritis.
Your muscles: Keeping
you strong and active!
J
ust as there are different types of joints, your body also has different types of muscles. Voluntary, or skeletal, muscles are controlled by you. When you
consciously move, you are working your
voluntary muscles. They are made of long
layers of fibers that look like light and dark
stripes when viewed under a microscope.
Voluntary muscles make up about 40 percent
of an adult’s body weight. They are connected
to your bones by tendons, or cords made of
strong tissue. Tendons enable your bones to
move when you contract your muscles.
Voluntary muscles work in groups each time
you move. The muscle that creates the movement is called the agonist, or prime mover.
The agonist works with the antagonist,
a muscle that creates the opposite effect on
the bone. You might have heard of protagonists and antagonists in stories. While those
opposing forces work against each other,
your agonist and antagonist muscles are
opposing forces that work together to
create a movement.
Cardiac muscles can stretch only in certain
ways like other voluntary muscles, but have
the powerful force of voluntary muscles.
Involuntary muscles in your digestive system
are hard at work after the voluntary muscles
in your mouth chew food. Most of the
muscles of the organs in your digestive
system are called smooth muscles because
of their smooth, uniform appearance
(in contrast to the striped
appearance of voluntary muscles).
Involuntary muscles, on the other hand,
move by themselves. For example,
muscles in your heart, called
cardiac muscles, keep your
blood flowing. Unlike most
other muscles, cardiac
muscles are connected
only to each other,
and not to bone.
Muscle shapes
Muscles have four general shapes. When
you use these muscles, whether in sports or
in your everyday routine, try to picture their
movement as the shape described.
n Circular muscles are ring-shaped and
located around your mouth and eyes. The
muscles around your eyes are unique because
they are both voluntary and involuntary. Why
do you think that is? Think about all of the
important movements these tiny muscles
make every day.
n The involuntary muscles in your stomach,
called your abdominals, are an example of flat
muscles. Your forehead muscles are also flat
muscles. Both of these muscles stretch flat
across these parts of your body.
n Your biceps and triceps muscles in your
arms are shaped like spindles, thick in the
middle and thin at the ends. When you flex
your bicep, for example, you can see the bulge
in the middle of the muscle. Another name for
spindle-shaped muscles is fusiform muscles.
n Your deltoid and pectoral muscles, found
across your shoulders, are triangular in shape.
When you lift an item from a high shelf or just
raise your hand in class, you are using your
deltoids and pecs. These groups of muscles
are called triangular because the origin of the
muscle (the part that attaches to the bone) is
wider than the other end. Triangular muscles
are also called convergent muscles.
Your lower jawbone is the only bone in your head you can move.
Working in pairs
s
e
l
c
s
u
m
w
Ho
work
Muscles are made up of fibers that contain smaller
bundles, called sarcomeres, connected end to end.
These bundles of cells are wrapped in a thin skin called
perimysium. All muscles have these bundles; in fact,
the bigger the muscle, the more bundles inside.
Muscles operate by contracting. During the
contraction, the ends of each sarcomere pull toward
each other. After the contraction, the sarcomeres are
shorter. This simple pulling action is responsible
for many of your movements.
Strengthen and
protect your muscles
Just as strength training and aerobic exercise help your bones
and joints stay strong, regular exercise is very important for
healthy muscles, too. Aerobic exercise, which gets your heart
pumping, not only keeps your heart muscles strong, but
also works muscles throughout your body.
Which of the muscles you learned about are hard at work
when you’re swimming, running or dancing? How are these
movements different from each other?
Your forearm
contains pairs of
muscles that move
your hand and fingers
back and forth.
When the
triceps muscle
contracts, it straightens
your arm.
Let’s take a closer look at the action within the sarcomeres.
Sarcomeres contain two types of protein: myosin and actin.
Myosin is a thin protein with a head on it, like a pushpin. Within
a sarcomere, myosin proteins are bundled together with the heads
pointing out; picture a bundle of flowers joined at the base
of the stems.
The actin protein is round, like a ball. These balls are linked
together like beads of a necklace to create a long filament. The
myosin and actin are arranged in alternating rows in order for
the sarcomeres to contract. The myosin heads connect to the
actin and pull them inward, which is why the length of the
muscle fiber is shortened when the muscles are contracted.
When the biceps muscle
contracts, it pulls your
forearm and bends your arm.
Sources
http://www.nsbri.org/default/Documents/EducationAndTraining/Muscles/MB_Guide.pdf
Some people
call the humeru
s bone
the “funny bone”
because
it sounds like “h
umorous.”
But when you b
ump
your elbow, you
won’t think
it’s so funny.
http://www.brainpop.com/educators/community/lesson-plan/muscles-moviebackground-information-for-teachers-and-parents/?bp-jr-topic=muscles
http://library.thinkquest.org/10348/
http://kidshealth.org/kid/htbw/muscles.html
http://kids.discovery.com/tell-me/science/body-systems/your-muscular-system
http://www.bbc.co.uk/science/humanbody/body/factfiles/skeletalsmoothandcardiac/
quadriceps_animation.shtml
http://science.howstuffworks.com/life/human-biology/muscle1.htm
http://www.olympic.org/sochi-2014-winter-olympics
http://kidshealth.org/teen/your_body/body_basics/bones_muscles_joints.html
http://hes.ucfsd.org/gclaypo/skelweb/skel01.html
http://www.bbc.co.uk/science/humanbody/body/factfiles/joints/ball_and_socket_joint.shtml
https://sites.google.com/a/jeffcoschools.us/mr-volk-s-science-website/science-content/
circulatory-and-respiratory-systems/skeletal-and-muscular-systems
http://kidshealth.org/kid/htbw/bones.html
http://www.brainpop.com/educators/community/lesson-plan/bones-moviebackground-information-for-teachers-and-parents/?bp-jr-topic=bones
http://www.coreknowledge.org/mimik/mimik_uploads/lesson_plans/115/Bones%20
Bones%20Bones%20Exploring%20the%20Skeletal%20System.pdf
http://www.brainpop.com/educators/community/lesson-plan/bones-activities-for-kids/?bp-jr-topic=bones
http://www.scholastic.com/teachers/lesson-plan/super-skeletons
http://www.coreknowledge.org/mimik/mimik_uploads/lesson_plans/115/Bones%20Bones%20
Bones%20Exploring%20the%20Skeletal%20System.pdf
http://teachhealthk-12.uthscsa.edu/curriculum/bones/pa12pdf/1202E-SHO.pdf
http://www.enchantedlearning.com/subjects/anatomy/skeleton/
http://www.kidport.com/RefLib/Science/HumanBody/BodyBones.htm
http://www.kidcyber.com.au/topics/bodybones.htm
http://www.cyh.com/HealthTopics/HealthTopicDetailsKids.aspx?p=335&np=152&id=2523
http://caloriecount.about.com/calcium-rich-smoothie-recipe-r1072763
http://www.innerbody.com/image_skel07/skel33.html
http://www.webmd.com/health-insurance/protect-health-13/exercise-bones
Each one of your hands has 27 bones.
http://www.doctoroz.com/blog/mao-shing-ni-lac-dom-phd/4-natural-ways-protect-your-joints
http://www.colorado.edu/outreach/BSI/pdfs/muscleContraction.pdf
Let’s say you played an intense game of basketball, and now
your leg muscles are aching. Applying an ice pack to a sore
muscle for a short period of time can help to ease the pain.
However, it’s recommended that you do all you can to prevent
muscle strains in the first place. The best method is to warm up
before physical activity and stretch your muscles afterward.
Below are a few easy stretches for your leg muscles; be sure
to stretch both sides for balance.
n Your quadriceps are the muscles at the front of your thighs.
For a simple quad stretch, stand on one leg with your hand on
a wall or chair for support. Bend your other knee and pull your
foot behind you, as close to your bottom as possible. Hold
the position for a gentle stretch.
n Your hamstrings are the muscles at the back of your calf. You
can do several easy hamstring stretches while sitting on the floor.
First, stretch your legs out straight and bend over them as far as you can
without straining the backs of your knees (keep them slightly bent).
Another easy stretch: Extend one leg across the floor and bend the other
so that your knee points to the side and the bottom of your foot
meets your inner thigh. Then
bend over your
n Your illiotibial (IT) band runs from the outside
extended leg.
of your hip to your knee. To stretch this muscle,
stand with your ankles crossed. Then lean with your
arm raised to the side of the ankle in back. You
should feel the stretch along the front hip.
Career options
There are several careers in the health and medical field related to
the musculoskeletal system. Doctors such as orthopedic surgeons
probably come to mind, but health-care professionals such
as massage therapists also apply their knowledge of bones,
joints, and muscles to provide treatment.
Many jobs in the field of dentistry study bones and muscles
around the face and neck. Interested in X-rays? Radiographers and radiologists operate X-ray equipment and
interpret the films. Physical therapists, occupational
therapists, rehabilitation therapists and chiropractors use
their understanding of this complex body system in treating patients. If you like animals, consider studying bones,
joints and muscles in the field of veterinary science.
X-rays and MRIs offer a closer look
How to prevent
sore muscles
X-ray is another term for electromagnetic radiation. This is a way to produce
images of your body, especially your
bones, by using electromagnetic beams.
Because your bones absorb rays, while
your skin and muscle allow rays to pass
through them, we are able to see bones
projected in white with the skin and
muscle in gray and black.
An X-ray is the simplest method for
producing an image of bones. In the case
of a bone and joint injury such as a knee
injury, an MRI (magnetic resonance
image) might be taken. An MRI can
capture an image of your body by using
a scanner instead of an X-ray. MRIs can
reveal more subtle tears or fractures
than X-rays.
Activity
Make a
model of a bone
Use a cardboard paper-towel or
toilet-paper tube as the
periosteum and compact bone.
Line the tube with a thin layer
of sponge to represent the
cancellous bone. INside the sponge
layer, insert small pom poms
or cotton balls to represent
the marrow.