shape and support the body
BONES
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The skeletal system has 5 functions: |
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shape and support the body |
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| allows movements | |
| protect tissues and organs |
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| store certain materials | |
| produce blood cells |
Bones are living tissues and contains
cells, nerves, and blood vessels.
Bones may be long,
short, flat, or irregular in shape. Long
bones are responsible for stature and reflect increases in height as a person
ages.
Wide, flat bones are
used as anchors for attachments of several muscle groups.
Examples of long
bones are the main bones in the arms and legs.
Examples of flat bones are in the hips and shoulders.
The primary
function of bones is to support and give shape to the body and to provide
protection for the soft internal structures.
They are among the toughest of all living
tissue, but are also one of the lightest materials in the body and only account
for 14% of total body weight.
There are 206 bones in the human skeleton.
AXIAL
SKELETON
skull,
vertebrae, ribs, sternum
APPENDICULAR SKELETON
arms and legs
Bones are connective tissue consisting of a membrane of
fibers and cells containing calcium salt.
Bones start as soft, flexible cartilage and gradually
harden into hard bone over a period of several years.
A bone is like a tube. The outside is made of hard, dense compact bone.
A living skin called periosteum covers the bone.
Inside is a jelly-like tissue called marrow.
There are 2 types of marrow found in bones.
Red marrow is located in the ends of long bones, such as
arm and leg bones, sternum, ribs, vertebrae, and parts of the skull.
Red marrow manufactures red and white blood cells the
body needs to survive.
This is the marrow that is tested when such blood diseases
as leukemia is suspected.
Marrow extraction for testing is usually taken from the
sternum, located in the front of the chest.
Marrow for transplanting is taken from the pelvis.
Yellow marrow is located in the center of other bones.
It stores necessary fats and minerals.
The skull consists of 8 curved bones linked firmly at
wiggly lines called sutures.
Suture joints are flexible at birth, but harden over time
as a baby grows and are not moveable by about the time a child reaches his
second year.
The skull’s purpose is to protect the brain and cushion
blows to it.
SPINAL
COLUMN
There are 24 vertebrae in a human body.
Between each of these vertebrae are washer-like disks of
flexible cartilage.
This cartilage is a tough, elastic tissue that allows
movement between the vertebrae. It also cushions the pieces of the spine so that
they do not rub against each other.
When a person stands and walks, each
disk is squashed by at least a cm.
When a person lies down, these disks return to their normal size.
There are 5 main parts to the spinal column.
Supports
the neck and skull and consists of 7 vertebrae
Supports
the thorax (chest of 24 ribs) and consists of 12 vertebrae
Carries
most of the body’s weight and consists of 5
Fusion of 5 sacral vertebrae into 1 vertebra
that transmits body weight to the hip joints
COCCYX
2-4
fused coccygeal vertebrae that represents tail of our ancestors
THORAX
Consists
of 21 flexible ribs joined by cartilage. Their
purpose is to protect the structures (heart and lungs) inside the chest.
The ribs connect to a fibrous, spongy bone
in front called the sternum.
BONES
OF THE BODY
SHOULDER
There
are 3 bones that make up the area of the body called the shoulder. They are the
scapula, clavicle, and humerus.
The 3 bones of the arm are the humerus,
radius, and ulna
HAND
There
are 27 small bones that connect the hand to the arm at the wrist area.
We are going to combine them into three main groups: the carpals, metacarpals,
and phalanges.
HIPS
The
bones in the hips are grouped together and called the pelvis or pelvic girdle.
There are 4 major bones that combine to
make a leg. They are the femur, tibia, fibula, and the patella, which is also
known as the kneecap.
As with the hand, there are many small
bones that are in the ankle area where the foot attaches to the leg. There are a
total of 26 bones in the foot. We are going to group them into 3 main groups.
They are the tarsals, metatarsals, and phalanges.
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