Body Movements

Class 6 Science | CBSE NCERT Curriculum

This chapter explains the human skeletal system, types of joints (ball and socket, hinge, pivotal, fixed), muscles, cartilage, and movement in animals including earthworm, snail, cockroach, fish, birds, and snakes.

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Quick Revision: Body Movements

  • Skeleton: Framework of bones and cartilage giving shape to the body. Adult human has 206 bones.
  • Ball and Socket Joint: Rounded end of one bone fits into cavity of another. Allows movement in all directions (shoulder, hip).
  • Hinge Joint: Allows back-and-forth movement like a door hinge (elbow, knee, fingers).
  • Pivotal Joint: Cylindrical bone rotates in a ring. Allows head to turn left/right and bend forward/backward (neck).
  • Fixed Joint: Bones cannot move. Found in skull (upper jaw to head).
  • Cartilage: Soft, bendable tissue found in ear, nose, and between bones to prevent friction.
  • Muscles: Work in pairs - one contracts while the other relaxes. Muscles can only pull, not push.
  • Rib Cage: 12 pairs of ribs forming a protective cage for heart and lungs.
  • Backbone: Made of 33 vertebrae, allows bending.
  • Earthworm: No bones; moves by muscle contraction/extension using bristles.
  • Snail: Moves using muscular foot. Shell is outer skeleton.
  • Cockroach: Outer skeleton (exoskeleton). Three pairs of legs, two pairs of wings.
  • Birds: Hollow, light bones; forelimbs modified into wings; strong breast muscles.
  • Fish: Streamlined body; swims by curving body alternately; fins maintain balance.
  • Snake: Long backbone with many muscles; moves by making loops against ground.

Chapter Summary: Body Movements

This chapter explores how humans and animals move. The human skeleton comprises bones and cartilage, forming joints that enable various movements. Ball and socket joints (shoulder, hip) allow all-direction movement. Hinge joints (elbow, knee) allow back-and-forth movement. Pivotal joints (neck) allow rotation. Fixed joints (skull) allow no movement. Muscles work in pairs to pull bones. Different animals have adapted unique movement methods: earthworms use muscle contraction with bristles; snails use a muscular foot; cockroaches have an exoskeleton with legs and wings; birds have hollow bones and strong flight muscles; fish have streamlined bodies and swim by curving; snakes slither using body loops. Yoga helps maintain healthy bones, muscles, and joints.