Lever Systems: Bone-Muscle Relationships

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Lever Systems Bone-Muscle Relationships
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Bone-Muscle Relationships Lever Systems

• Lever- rigid bar free to turn about fixed point
  ex. bone
• a. Fulcrum- fixed point
• ex. joint
• b. Load- resistance moved L
• ex. part of body
• c. Force- pull from contraction F
• ex. muscle

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Bone-Muscle Relationships Lever Systems
Mechanical advantage
Figure 10.2a
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Bone-Muscle Relationships Lever Systems
Mechanical disadvantage
Figure 10.2b
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Lever Relationships

• Effort farther than load from fulcrum equals
  mechanical advantage
• Effort nearer than load to fulcrum equals
  mechanical disadvantage

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Lever Systems Classes

• a. 1st Class- Fulcrum between Load Force
  seesaw
• stability
• Ex. Head tilt
• b. 2nd Class- Load between Fulcrum Force
  wheelbarrow lift
• Ex. Raising body with toes
• c. 3rd Class- Force between Fulcrum Load
  shovel rapid movt
• Ex. Flex forearm

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Lever Systems Classes
Figure 10.3a
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Lever Systems Classes
Figure 10.3b
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Lever Systems Classes
Figure 10.3c
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Machines of the Body
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Prime movers and synergist muscles
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Agonist and antagonist muscles
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Apart from assisting in locomotion does the
muscular system play any other role?
Posture this includes the erector spinae muscles
and the muscles of the trunk.
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Salient points
Muscle groups are classified upon the the
arrangement of the muscles fibres, this provides
a wide range of muscle types.
The origin of the muscle is that attachment at
which the bone is stationary
The insertion of the muscle is at that
attachment where the bone is moving
Muscle can have several different roles they
can be agonists, antagonists and synergists
Not all muscles are involved in locomotion,
they also enable other important bodily
functions, for example, respiration, provide
movement for the eye, assist in swallowing and
speech
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Major Skeletal Muscles Anterior View

• The 40 superficial muscles here are divided into
  12 regional areas of the body

Figure 10.4b
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Major Skeletal Muscles Posterior View

• The 27 superficial muscles here are divided into
  seven regional areas of the body

Figure 10.5b
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