Muscles

• Antagonistic muscles

  • Arranged in pairs so that one contracts and the other relaxes.
  • Bicep = 2 tendons; Tricep = 3 tendons
  • When the bicep contracts & the tricep relaxes, the arm bends.
  • When the tricep contracts & the bicep relaxes, the arm extends.
• Structure of skeletal muscle

  • Each muscle is made of many muscle fibres bound by a connective tissue.
  • Each bundle is bound by connective tissue to form a complete muscle.
  • Muscle fibres are cylindrical and elongated.
  • Muscle fibres consist of myofibrils(myosin & actin)
  • Myosin filament are thick and dark
  • Actin filaments are thin and light.
  • This colour change creates a striated appearance.
  • During contraction, actin filaments slide over the myosin filaments, creating an overlap and a shortening of myofibrils and the whole muscle.