Chapter: Body Movements

• Introduction

  • Meaning of Movement and Locomotion
  • Importance of movement in daily life
  • Variety of movements in animals and humans

• Human Body and Its Movements

  • Skeleton (Framework of Bones)
    • Gives shape and support
    • Protects internal organs
    • Number of bones in an adult human (206 bones)
  • Skull
    • Protects the brain
  • Backbone (Vertebrae)
    • Made of many small bones
    • Allows bending
  • Rib Cage
    • Protects heart and lungs
    • Joins chest bone and backbone
  • Shoulder Bones and Pelvic Bones
    • Support limbs (arms and legs)
  • Cartilage
    • Additional skeletal parts
    • Softer and more flexible than bones (e.g., earlobe)

• Joints

  • Places where two parts of the skeleton meet
  • Types of Joints:
    • Ball and Socket Joint
      • Allows movement in all directions
      • Example: Shoulder and hip
    • Pivotal Joint
      • Cylindrical bone rotates on a ring
      • Example: Neck (joins head to backbone)
    • Hinge Joint
      • Back-and-forth movement in one plane
      • Example: Elbow and knee
    • Fixed Joints
      • Bones cannot move at these joints
      • Example: Upper jaw and skull

• Muscles

  • Fleshy bundles attached to bones
  • Work in pairs (contraction and relaxation)
  • Pull bones to cause movement; cannot push

• Gait of Animals (How Animals Move)

  • Earthworm
    • Moves by muscle contraction/relaxation and bristles (setae)
    • Secretes slimy substance for grip
  • Snail
    • Moves using a muscular foot
    • Pulls a hard shell along
  • Cockroach
    • Walks, climbs, and flies (three pairs of legs, two pairs of wings)
    • Hard outer skeleton (exoskeleton)
  • Birds
    • Streamlined body for flight
    • Forelimbs modified as wings
    • Hollow bones (pneumatic bones) and strong flight muscles
  • Fish
    • Streamlined body shape to cut through water
    • Fins for steering and balance
    • Tail muscles create side-to-side waves for forward movement
  • Snakes
    • Slithers on the ground by forming loops
    • Backbone, curves, and scales help push against the ground