274Bones
Your bones form a framework for your
body called a skeleton. If you did not have
a skeleton your body would flop all over
the place. Bones also protect your soft
internal organs (such as your heart) and
work with muscles to make you move.
Arteries (red) supply
nutrients and oxygen
to the bone’s cells.OThere are 206 bones in the human body.
OCompared to a steel bar of the same
weight, bone is six times stronger.
OYour largest bone is your femur. Your
smallest bone is the stirrup bone, which
is in your ear. It’s no larger than a grain
of rice.
OAbout eighty bones make up the human
skull, backbone, and ribs.
OYou need calcium in your diet to make
your bones hard.
OYou have the same number of neck
bones as a giraffe: seven.
OA baby’s skeleton is largely formed of
cartilage (the stuff that makes your nose
flexible).
OThe thigh bone (femur) is the longest
bone in your body. It is about a quarter of
your height.
OMore than a quarter of your bones are
in your hands.Inside a bone
Bones are made up of
layers, with hard, compact
bone on the outside and spongy bone
beneath. The spaces in some bones are filled
with jellylike bone marrow. Bone marrow
stores fat and also produces new blood cells.The kneecap
(patella) protects
the front of
the knee INSIDE A JOINT
The ends of your bones (in
blue below) are covered by
smooth cartilage and
separated by fluid, so
the bones easily slide
over each other.An inner layer of
spongy bone is light in
weight but also strong.The pelvic (hip)
girdle supports
abdominal organs
and anchors the legs.Pieces of the skull
Your skull is not made
up of one bone, but of
a large number of
bones. The pieces of the
upper skull lock together
to form an incredibly
strong casing for your
brain, while fourteen bones
form your facial bones. The
shape of your facial bones
and their muscles determines
what you look like.The heel
(calcaneus) is
a short bone.Blood cells are made
in the bone marrow.The thigh bone
(femur) is the
largest bone in
the body.FAST FACTS
THE HUMAN BODY