Muscular system

• Antagonistic muscles


  Pairs of muscles that work against each other
• Antagonistic muscle action

  1. One muscle contracts while the other one relaxes, and vice versa

  2. The muscle that's contracting is the agonist

  3. The muscle that's relaxing is the antagonist

  4. Each muscle is attached to two bones by tendons

  5. Only one of the bones connected at the joint actually moves
• Fixator muscles


  Muscles that stabilise the agonist where it attaches to the bone that doesn't move
• Fixator muscles


  • Deltoid and trapezius for elbow flexion
  • Abdominals for knee and hip movements
• The muscle that's the agonist in one movement will be the antagonist in the opposite movement
• Antagonistic muscles pairs

  • ELBOW: Flexion - agonist - biceps, antagonist - triceps

  Extension - agonist - triceps, antagonist - biceps

  • KNEE: Flexion - agonist - hamstrings, antagonist - quadriceps Extension - agonist - quadriceps, antagonist - hamstrings
  • SHOULDER: Flexion - agonist - front deltoid, antagonist - back deltoid Extension - agonist - back deltoid, antagonist - front deltoid Adduction - agonist latissimus dorsi, antagonist middle deltoid Abduction - agonist middle deltoid, antagonist latissimus dorsi
• Muscles are needed to move bones

  • The muscles that enable movement are attached to bones by tendons
  • when you contract a muscle it pulls on the tendon, which pulls on the bone, making it move
  • during exercise, muscles need oxygen so they can move the body
  • when the heart beats, it pumps blood carrying oxygen to these muscles
• Pectorals


  Adduction and flexion at the shoulder

  e.g during a forehand in tennis
• deltoids

  flexion, extension, abduction or circumduction at the shoulder

  e.g during front crawl in swimming
• trapezius


  extension at the neck

  e.g heading in football
• abdominals


  flexion at the waist

  e.g during a sit up
• biceps


  flexion at the elbow

  e.g during bicep curl
• triceps


  extension at the elbow

  e.g during a shot in basketball
• quadricep


  extension at the knee

  e.g drop kick in rugby
• hamstring


  flexion at the knee

  e.g bringing foot back before kicking a football
• Latissimus dorsi

  Extension, rotation and adduction at the shoulder

  e.g during butterfly stroke in swimming
• gluteals


  extension, rotation and abduction of the leg at the hip

  e.g pushing the body forward when running
• gastrocnemius (calf)


  Pointing the foot downwards

  e.g ballet standing on toes