The Skeletal SystemStrong & Living, Structure of Bones,

How Bones Form, Joints, Taking Care of Bones, Diagnosing Bone and Joint Injuries

The word “skeleton” actually comes from a Greek word meaning “a dried body” but your bones are very much alive!

Bone Strength◦Strong & lightweight◦Can absorb more force without breaking than

concrete◦Only make up about 20% of your weight◦Made of minerals like phosphorus and calcium.

Bones—Strong and Living

Basically, if you weighed 100 lbs,then your bones would make up 20 lbs

and the leftover 80 would be muscle and fat.

Bone Growth◦Bones are constantly creating new bone

tissue as you grow◦Bones absorb the force of your weight when you

move, so new bone tissue is needed.◦Bone tissue grows to fill in the gap between

broken ends of the bone.

Bones—Strong and Living continued!

All bones are covered in a tough outer membrane◦This is where blood vessels enter and leave the

bone Beneath that is a layer of hard compact

bone Has small canals with blood vessels running through it.

The Structure of Bones

Spongy bone is found at the ends of bones◦Contains many small spaces ◦Keeps bones light

Marrow is found beneath compact bone and between spongy bone.◦Two types of marrow: red and yellow◦Red marrow produces red blood cells◦Yellow marrow stores fat for energy

The Structure of Bones continued!

Cartilage is a connective tissue that is more flexible than bone.◦Also covers many ends of bones as a “cushion” for

joints. As an infant, you are born with more cartilage

in your skeleton that is replaced with bone as you grow older.

By the time you stop growing, most cartilage has been replaced by bone.

However, the cartilage in your nose, ears, ribcage, and between your joints will never by replaced by bone.

How Bones Form

How Bones Form Picture!

1-year-old

3-year-old

13-year-old

Take a few seconds and talk to the students at your table about what life would be like if your femur ran from your hip to your ankle.

How would your life be different?

Luckily, our skeleton has joints.

A joint is a place in the body where two bones come together.

Joints of the Skeleton

Our bodies have two kinds of joints

◦ Immovable – a place where two bones meet that allows for little or no movement.

◦Movable– allows the body to make a wide range ofmovements.

Joints of the Skeleton continued!

Bones are held together by strong connective tissue called ligaments.

More Joints!Ball-and-socket joint– allows for the greatest range of movement. Found in shoulders and hips.Pivot joint– allows one bone to rotate around another. Found in the vertebrae in your neck.

Hinge joint– allows extensive forward or backward motion. Found in your knees and elbows.

Gliding joint – allows one bone to slide over another. Found in wrists and ankles.

Keep your skeleton healthy by combining a balanced diet and regular exercise.

Your diet should include:◦Calcium and phosphorus◦Meats, grains, and leafy green vegetables◦Also dairy products

Get plenty of exercise!◦Walking, sports, skateboarding, aerobics, etc.

Taking Care of Your Bones

As people get older, they begin to lose some minerals within their bones.

Osteoporosis is a condition in which body’s bones become weak and break easily.

Taking Care of your Bones

How can we prevent this?

Common skeletal injuries◦Fracture – A break in a bone◦Sprain – Occurs when ligaments are stretched

too far and tear in places Most common joint injury

◦Dislocation – Occurs when a bone comes out of its joint Sometimes doctors can put the bone back in place Sometimes individuals may need surgery

Diagnosing Bone and Joint Injuries

An x-ray image of a broken bone.

X-rays are a form of energy that travels in waves Helps us determine whether bones are broken

Because most x-rays pass through the skin and other body tissues, the X-rays strike the photographic film beneath the area. Unlike other body tissues, bone absorbs X-rays.

X-Rays: A Look Inside the Body

A new method was developed in 1970 that showed clear images of both bone and soft tissue.

Known as an MRI, the machine sends off magnetic energy that makes body molecules vibrate or resonate.

Magnetic Resonance Imaging