PSIO 3.1

• Basic function of all three muscle types

  • Generate Tension
• Functions of skeletal muscle

  • Locomotion
  • Facial expression
  • Posture and body position
  • Regulation of body temperature
• Skeletal muscle contraction

  Voluntary, requires nervous system input
• Origin

  Where muscle starts on a bone, stationary
• Insertion

  Where muscle ends on a bone, moves toward the origin
• Reverse muscle action

  When the insertion is anchored, the origin moves towards the insertion
• Reverse muscle action example

  • Pull-ups
• Action: leg extension

  
  

  Muscle group: quadriceps

  Origin: femur

  Insertion: tibial tuberosity
• Agonist

  Muscle primarily responsible for the movement (prime mover)
• Antagonist

  Muscle that opposes action of agonist
• Synergist

  Assists the agonist to make action more efficient
• Fixator

  Special synergists that help prevent movement at muscle origin
• Lever

  Rigid bar (bone) that moves around a fixed point (joint)
• Fulcrum

  Fixed point around which the rigid bar (bone) moves → (joint)
• Purpose of lever systems in the body

  • Facilitate movement at a fulcrum (joint) by exerting force on the lever (bone) to move a load