CBSE Notes Class 6 Science Chapter 5 Body Movements 

The ability to move has been used as a criterion to differentiate plants and animals. Though movement is quite common in plants, it is not always apparent. Animals possess definite organs for locomotion. The act of moving from place to place is known as locomotion. It involves the movement of the whole body as in walking, running, swimming or flying. Movement is the change in position of only a part of the body, as movement of stem towards light in plants. 

1.0Human Body & Its Movement

Skeletal System

The skeleton consists of Skull, Backbone, Ribs, Breastbone, Shoulder bones, Hip bone, Arm bones and Leg bones.

1. Skull 

• The bones of the skull form a strong case around the brain. In this way, the skull protects the brain. 
• The skull also protects the main sense organs like eyes, ears and nose. 
• The eyes are contained in two large cavities called 'eye sockets' in front of the skull.

2. Backbone 

• The backbone is a long, hollow, rod-like structure running from the neck to the hips, inside our body. 
• The scientific name of backbone is vertebral column. Backbone forms the main supporting structure of the body.

3. Rib Cage 

• If we take a deep breath, hold it for a while and move our hand on the chest, we will find a number of bones in the chest region. 
• These chest bones are called ribs. Ribs are the curved bones in our chest. Ribs exist in pairs. There are 12 pairs of ribs in the chest of our body. 
• The hollow, bony structure formed by the ribs is called 'rib cage'. 
• Ribs are attached in front to breastbone or sternum and at the back they are attached to backbone.

4. Shoulder bones 

• Shoulders are that part of the body (or skeleton) to which our arms are attached. 
• The human body has two shoulders, one on each side of the neck. 
• There are two shoulder bones : collarbone and shoulder blade. 

5. Hip Bone 

• The thigh bones of our legs are joined to the hip bone by the ball and socket joints. 
• Actually, the hip bone forms the link between the upper part of our body (called trunk) and the legs.

6. Bones of the Hand 

• The hand consists of various small bones which form the wrist, palm and fingers. 
• Our hand is made up of three parts : wrist, palm and fingers.

7. Joints 

The structural arrangements of tissues by which bones are joined together are called joints. According to the mobility, joints are classified as :-

Immovable joints/fixed joints : In some joints, the bones are held so tightly together that they cannot move at all. Such joints are called fixed joints. These joints allow no movement. For example, the bones of the skull are interlocked with each other by their serrated margins called sutures, joints in tooth sockets, and the upper jaw. 

Slightly movable/ cartilaginous : In these joints, a pad of flexible cartilage is present between the bones which make slight movement possible. Such joints are present between adjacent vertebrae in the backbone. 

Freely movable joints : These joints allow free movement of bones in various directions. These are also known as synovial joints. 

• Ball and socket joint : In this joint, the rounded head (like a ball) of one bone fits into a cup-shaped cavity formed by the other bone . This allows movement in all directions. For example, you can move your shoulder and hip in all directions. 
• Hinge joints : The hinge joints allow the movement only in one direction (back and forth movement) like those of a door or the lid of a box. Elbow joints (joints between the upper and the lower arm), knee-joint (between thigh and lower leg) are examples of this type of joint. 
• Pivot joint : Such joints allow rotation only. Pivot joint occurs where our neck joins the head. It allows the head to move backward and forward and turn the head to our right or left. The head rotates over a cylindrical bone of the neck. 
• Gliding joint : Also known as plane joint. It allows the bones to glide past one another providing little movement. e.g. at the ankle and carpals in the wrist.

2.0Cartilage 

• Some additional parts of the skeleton that are not as hard as the bones and which can be bent. 
• These are cartilage. 
• Cartilage is soft, smooth and elastic tissue. 

Muscular System 

• Muscular system consists of muscles which help in locomotion and movement. Locomotion is the result of co-ordinated action of muscles of the limb bones. 
• The contraction and relaxation of muscles move the bones. 

3.0Gait in Animals

1. Earthworm

• The earthworm's body is made of many rings joined end to end and has no bones, but muscles that help it extend and contract for movement. 
• It moves by extending the front part, fixing it to the ground, then pulling the rear end forward. 
• A slimy secretion aids this process, while tiny bristles under its body provide grip. 
• Earthworms eat their way through soil, expelling undigested material, which helps improve soil quality for plants.

2. Snail 

• A snail moves using its large, disc-shaped muscular foot, which secretes fluid to glide smoothly. 
• The shell is dragged along since it can't move on its own. 
• Two sets of muscles in the foot contract and expand alternately, creating a wave-like motion that propels the snail forward.

3. Cockroach 

• Cockroaches are nocturnal insects capable of walking, climbing, and flying. 
• They have two pairs of wings and three pairs of legs for movement. 
• Without bones, their body is protected by a hard outer skeleton made of interconnected units, allowing flexibility. 
• Muscles near the legs aid in walking, while breast muscles enable flight.

4. Fish

Fish have several adaptations that aid in movement:

• Flexible Backbone:  A fish's flexible backbone allows it to bend its body easily from side to side, enabling smooth movement through water.
• Fins: Fins, the thin and flat projections on the fish's body, assist in steering, balancing, stopping, and propelling forward. The tail fin is crucial for forward movement.
• Powerful Muscles:  Strong muscles on both sides of the fish help move the tail side to side. This motion creates jerks that push the fish forward, aided by the tail fin for swimming. Other fins help maintain balance and direction.

5. Snakes

• Snakes have a long backbone and numerous thin muscles connected to the backbone, ribs, and skin. 
• They move by crawling, contracting and relaxing muscles on both sides of their body alternately to form loops. 
• Each loop pushes against the ground, propelling the snake forward, allowing it to move quickly.

6. Birds

• Birds are adapted to fly, walk, and some, like ducks and swans, swim. 
• They use their hind limbs to walk and swim, with webbed feet aiding in swimming. 
• Key adaptations for flight include:
• Forelimbs modified into wings.
• Large, lightweight flight feathers.
• Hollow, light bones.
• Streamlined, lightweight bodies.
• Powerful flight muscles.
• Extended breastbone for muscle attachment.