The Skeletal System, Bones and Joints

This week is Halloween and we are studying...
The Skeletal System, Bones and Joints!

What is a Bone?

n  The skeletal system is made up of the bones and cartilage that forms the framework of your body.
n  We have bones so that we are not a puddle of skin and guts on the floor.
n  Babies have 300 bones.
n  Adults have 206 bones.

What is the Skeletal System?
        Your Skeletal system is all of the bones in the body and the tissues such as tendons, ligaments and cartilage that connect them.

Your teeth are also considered part of your skeletal system but they are not counted as bones. Your teeth are made of enamel and dentin. Enamel is the strongest substance in your body.


What is the Function (or purpose) of the Skeletal System

The main job of the skeleton is to provide support for our body. Without your skeleton your body would collapse into a heap. Your skeleton is strong but light. Without bones you'd be just a puddle of skin and guts on the floor.
Your skeleton also helps protect your internal organs and fragile body tissues. The brain, eyes, heart, lungs and spinal cord are all protected by your skeleton. Your cranium (skull) protects your brain and eyes, the ribs protect your heart and lungs and your vertebrae (spine, backbones) protect your spinal cord.
Bones provide the structure for muscles to attach so that our bodies are able to move. Tendons are tough inelastic bands that hold attach muscle to bone.
More reasons we need bones...they make our BLOOD!
 In the middle of some bones is jelly-like bone marrow,
                         where new cells are constantly being produced for the blood.

 The Bones of the Skeletal System


Bones Connect at Joints

They connect with connective tissue...
Joints consist of bones, muscles, cartilage, tendons, ligaments and other connective tissue.
  • Tendon joins muscle to bone enabling movement.
  • Ligament joins bone to bone, stabilising the joint.


    When a bone is pulled out of its joint, a dislocation occurs.
    Ligaments are the tissue that hold bones in their joints. They are like very strong rubber bands. When a bone is dislocated, the ligaments are either stretched too far or torn. While you can put the bone back in by pulling on it and allowing it to snap back into place, you should be checked out by a doctor to make sure there is no damage to the ligaments and surrounding tissue. Plus, a doctor might recommend that a dislocation, even though put back into place, should be immobilized for a while to allow the surrounding area to heal from the shock and trauma.
    Basic Joint Anatomy

    Why is there little to no movement in a fibrous joint? Because the bones making them up are made of fibrous tissue, which is very tough.

    What is an example of a fibrous joint? The bones in your skull.

    Describe a cartilaginous joint and give an example. Very little movement occurs between a cartilaginous joint. It's formed by two bones that are united by intervening fibrocartilage. Example: Vertebrate of the spinal column are formed by intervertebral disks.

    What type of joint essentially allows free movement? Synovial joint.

    What lubricates a joint cavity? Synovial fluid.

    For the following joint types please list the name of the joint type, the type of movement of the joint, the shape of the joint and an example:

    Plane joint - gliding in any direction - slightly curved articular surfaces - carpal bones in the hand

    Hinge joint - rotation around a single axis - one irregular cylinder surface and one surface with a concave groove - the elbow joint

    Condylar joint - Similar to a hinge joint but permits more movement - two articular surfaces (condyles) - the knee joint

    Ball and Socket joint - many different directions - a spherical articulation fitting into a cup shaped cavity - the shoulder joint

    Ellipsoidal joint - much movement, like with the wrist joint - like the ball and socket joint, only the ball joint is oval shaped - the wrist joint

    Pivot joint - allows for two bones to pivot around one another - a bony peg that fits into a concave notch - the joint between the radius and ulna

    Saddle joint - many directions - resembles two western saddles - the joint at the base of the thumb .

    Coming soon... The Muscular System and Integumentary System (protects and covers the muscular system, the largest organ in the body... skin)


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