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"Dem Bones" are Levers
Gordon Engle Tim Evans Sandra Thompson August 4,
1999
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Dem Bones are Levers

• Classes of levers
• Radius and ulna are levers
• Force is applied by muscles

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Classes of levers

• First class levers have the fulcrum between the
  weight and the force.
• The ulna is a first class lever.

4
Classes of levers

• Second class levers have the weight between the
  fulcrum and the force.
• Where is an example of a second class lever in
  the body?

5
Classes of levers

• Third class levers have the force between the
  fulcrum and the weight.
• The radius is a third class lever.

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The force is applied by muscles.

• In the arm the biceps brachii and the triceps
  brachii work in opposition to each other to flex
  and extend the forearm.

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Biceps brachii

• The origin is the name for the attachment to the
  bone that doesnt move.
• Long head is attached to the supraglenoid
  tubercle and glenohumeral labrum.
• Short head is attached to the tip of the coracoid
  process of the scapula.

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Biceps brachii

• The insertion is the name for the attachment to
  the bone that does move.
• Radial tuberosity
• Bicipital aponeurosis

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Triceps brachii

• Origin
• Long head attaches to the infraglenoid tubercle
  of the scapula.
• Lateral head attaches to the upper half of the
  posterior surface of the shaft of the humerus,
  and the upper part of the lateral intermuscular
  septum.
• Medial head attaches to the posterior shaft of
  the humerus and lateral intermuscular septum

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Triceps brachii

• Insertion
• Posterior surface of the olecranon process of the
  ulna
• Deep fascia of the antebrachium

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Dem Bones are Levers

• Classes of levers
• Radius and ulna are levers
• Force is applied by muscles