How Do Muscles Work?

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How Do Muscles Work?
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Types of Movement.
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Flexion

• The decreasing of an angle between bones.
• One of the bones of the joint moves towards the
  other bone.

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Extension

• The opposite action to flexion.
• When the angle is increased between two bones.

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Abduction

• The movement of a limb or bone away from the
  body.
• HINT Abduction to take away.

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Adduction

• The movement of a limb or bone towards the body.
• HINT - Adduction to add to the body.

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Rotation

• A turning movement around a central point.

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Circumduction

• A movement which causes part of the body to form
  a complete circle.

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Muscles move by contracting.
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What happens when muscles contract?

• A muscle has to pull for contraction to occur.
• The muscle pulls on the bone to make it move
• Muscles cannot push to make movement happen.

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Muscles work in pairs.
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The working muscles.

• This is the muscle that contracts to allow
  movement.
• The relaxing muscles.
• When one muscle contracts, another relaxes to
  allow the movement to occur.

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Muscles work in pairs.

• E.g - The arm
• A flexed arm

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How are muscles attached to bones?
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Via Tendons.

• Tendons join the voluntary muscles to the
  skeleton.
• When the muscle contracts, the tendon pulls on
  the bone it is attached to and moves the bone.

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Where do they attach?

• Each muscle has an ORIGIN and an INSERTION.
• The origin is where the tendon of a muscle is
  anchored to a fixed point on the skeleton.
• The insertion is where the tendon is attached to
  the bone we want to move.

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E.g Biceps triceps action

• Origin of bicep
• The top of the scapula
• The glenoid cavity (in the shoulder).
• Insertion of bicep
• Near the elbow, in the radius.

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Activity!
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Turn to page 26 in your text books. Use it to
help you label the origin, insertion muscles on
the diagrams. Stick these in your work books
underneath the definitions of a tendon, origin
insertion.
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Homework!
Get out your planners.
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• To complete the sheet about muscles, how they
  move how they are attached.
• To be completed over the xmas holidays brought
  into the 1st lesson back.
• Dont forget a quick test that 1st lesson so
  use it to help with revision!