Body movements

• Locomotion is the movement of organisms from place to place
• In the human body, locomotion involves the human skeleton, which forms a framework providing shape and support
• The human skeleton consists of 206 bones and protects internal organs
• Parts of the human skeleton:

  • Skull: Protects the brain, rigid box made up of plates of bone firmly joined together
  • Rib cage: Flexible case of ribs, each rib curves round the side of the chest from the backbone and is joined in front to a plate of bone called sternum. Ribs are connected to one another by muscles. Two lowermost pairs of ribs are called 'floating ribs'
  • Backbone: Also called the spine or vertebral column, a chain of small bones called vertebrae. Protects the spinal cord, supports the skull, ribs, and limbs
  • Limbs: Made up of long bones with joints that allow movement, mainly for support
  • Arms: Forearms made up of two bones, hands have several small bones. Shoulder bones have a pair of collar bones in front and a pair of shoulder blades
  • Legs: Lower leg made up of two bones, feet have several small bones. Hip bones or girdles bear the weight of the body and are attached to thigh bones
• Joints are the points where two bones meet, allowing movement to take place. Bones are held together by ligaments
• Types of joints:

  • Movable Joints: Allow movement between bones and have cartilage between them
  • Hinge Joints: Allow movement only in one plane backwards and forwards. Examples include elbow joints, knee joints, and joints between phalanges of fingers and toes
• Types of joints:

  • Ball and Socket Joints: Permit circular movement. Example: the shoulder
  • Gliding Joints: Allow bones to slide a little. Example: bones inside wrists and feet
  • Pivotal Joints: Found where the neck joins the head. Allow the head to move backward and forward and turn right and left
• Immovable or Fixed Joints:

  • Bones cannot move at these joints. Example: bones in the skull, joint between upper jaw and rest of the skull
• Locomotion in other animals:

  • Fish: Achieved by lateral contractions of the muscular body with a final thrust by the tail. Swim by forming loops alternately on two sides of the body
  • Birds: Large flight muscles contract to pull the wings down
  • Snails: Muscular foot helps in locomotion
  • Earthworms: Move by stretching out the body in front and keeping the hind end fixed to the ground
• Bones are moved by alternate contractions and relaxations of two sets of muscles
• Bone joints vary depending on the nature of joints and the direction of movement they allow
• Strong muscles and light bones work together to help birds fly by flapping their wings
• Snakes slither on the ground by looping sideways. A large number of bones and associated muscles push the body forward
• The body and legs of cockroaches have hard coverings forming an outer skeleton. The muscles of the breast connected with three pairs of legs and two pairs of wings help the cockroach to walk and fly