Kinesiological Concepts of the Musculoskeletal System

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Kinesiological Concepts of the Musculoskeletal
System
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Properties of Striated Muscle

• Extensibility
• Elasticity
• Contractility
• Irritability

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Components of Muscle

• Contractile Component
• Macroscopic Level
• Entire muscle encased in epimysium
• Bundle of Muscle Fibers Fasciculus
• Each Bundle encased in perimysium
• Each Muscle fiber is a bundle of Myofibrils
• Bundle of Myofibrils encased in endomysium
• This is where the sarcomere is located

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Components of Muscle

• Miscroscopic Level
• Sarcolemma
• T-tubules
• Sarcoplasmic Reticulum
• Ca released
• Stimulates sarcomere to contract

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Components of Muscle

• Microscopic Level (Sarcomere)
• Actin
• Myosin
• Z-lines
• Tropomyosin
• Troponin

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Contraction Process

• Calcium released and binds to troponin
• Removes tropomyosin from binding site of troponin
• Myosin attaches to actin
• ATP causes a ratcheting affect (power stroke)

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Summary of Contraction Mechanical Process
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Components of Muscle

• Three Coverings
• Epimysium, perimysium and endomysium
• Series Elastic Component
• Located within tendon and connective tissue
  sheaths
• Release stored energy when muscle is stretched
• Parallel Elastic Component
• Negligible effect during contraction
• Stability and protection

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Muscle Classification based on Fiber Arrangement

• Fusiform (Parallel) Arrangment

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Muscle Classification based on Fiber Arrangement

• Fusiform (Parallel) Arrangment
• Pennate Muscles
• Unipennate

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Muscle Classification based on Fiber Arrangement

• Fusiform (Parallel) Arrangment
• Pennate Muscles
• Unipennate
• Bipennate

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Muscle Classification based on Fiber Arrangement

• Fusiform (Parallel) Arrangment
• Pennate Muscles
• Unipennate
• Bipennate
• Multipennate

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Muscle Classification based on Fiber Arrangement

• Fusiform (Parallel) Arrangment
• Pennate Muscles
• Unipennate
• Bipennate
• Multipennate
• Triangular or Convergent Muscle
• Quadrate Muscle

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Mechanics of Pennate and Parallel Muscles

• Parallel
• Long fibers but less fibers per cross sectional
  area
• Move body segment through large ROM
• Fast shortening speeds
• Pennate
• Greater number of fiber per cross sectional area
• Less ROM than parallel
• More force than parallel
• Slower shortening speed than parallel

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Muscle Attachments

• Tendons or aponeurosis to bone
• Origin
• Insertion
• Determining which is which is often confusing
• Line of Pull

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Muscle Classification by Relationship to
Articulations

• Uniarticulate Muscles
• Biarticulate Muscles
• Active Insufficiency
• Passive Insufficiency
• Why do we have biarticulate muscles?

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Types of Contraction

• Isometric
• Isotonic
• Concentric
• Eccentric

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Roles of Muscles

• Agonist (Movers)
• Antagonist

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Roles of Muscles

• Synergists
• Stabilizers, fixator and supporting role
• Contract statically to support or steady some part

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Roles of Muscles

• Synergists
• Stabilizers, fixator and supporting role
• Contract statically to support or steady some
  part
• Neutralizer
• Prevents unwanted accessory motion
• Influence of Gravity on Muscle Function

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Length-Tension Relationship

• Isometric tension greatest just beyond resting
  length
• Why?

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Force-Velocity Relationship

• Concentric Contractions
• Eccentric Contractions