NCERT Solutions: Class 6: Science: Body Movements

NCERT notes alongwith solutions for class 6: science – Chapter “Body Movements” are provided here. The notes as well as solutions are very much helpful for the students to understand the topic. The solutions will be handy for quickly completing the homework and preparing for exams.

Introduction: Body Movements

Animals and plants show a wide range of movements. Humans also display movements like moving limbs, jaws, eyelids, tongue, etc.

Do you know the term “Movement”?

Movement refers to a change in the position or posture of a body parts. It does not involve any change in location or displacement.

However, there are some of the movements which result in a change of place or location. Such movements are called locomotion like walking, running, climbing etc.
Locomotion requires a perfectly coordinated activity of muscular, skeletal and neural systems.

Do you know the term “Locomotion”?

When the movements result in a change of place or location, such movements are called locomotion.

Human body and its movements

Let’s examine some of our body movements in more detail, such as bending the arm from the elbow and the leg at the knee, turning the leg from the hip, and rotating the wrist up and down.
Have you ever wondered why some body parts move easily in multiple directions while others can only move in one direction? Why can’t we move certain body parts at all?
The answer will be that we are able to bend or rotate our body at points where two body parts appear to be connected together by bones —such as the elbow, knee, shoulder, neck, wrist, or ankle.
Without joints, our body parts cannot rotate or flex.

Do you know what exactly is joined together at these joints?

It is bones or different types of bones that are joined together at these joints. We can bend or move our body only at those points where bones meet.

Joints and its types

Joints

A Joint is a point of contact between bones or between bones and cartilage.
At the joint, bones or cartilage are connected with each other. Force generated by the muscles is used to carry out the movement through joints.

Types of Joint

There are four different types of joints in our body to help us carry out different movements and activities.

1. Ball and Socket Joint
2. Pivotal Joint
3. Hinge Joint
4. Fixed Joint

Ball and Socket Joint

A ball and socket joint is a synovial joint.
It is made up of two bones. The end of one bone is hemispherical, forming the ball, while the end of the other bone a cuplike depression, forming the socket.
The ball slides, rolls and spins within the socket to allow movement of the joint in multiple directions like:
- Flex
- Extend
- Rotate
- A back and forth motion
- A circular motion
The ball and socket joint is mainly found in two regions of the body:
1. Shoulder Joint – Formed at the point where the shoulder bone i.e. cup-shaped scapula (socket) is joined with the humerus bones (ball).
2. Hip Joint – Formed at the point where head of the femur (ball) is connected with the hip bone i.e. acetabulum of the pelvis (socket).

Pivotal Joint

A pivot joint allows rotation around a single axis only.
In this joint, a cylinder-shaped bone rotates inside the ring-shaped bone on a single axis.
Our skull is connected to the neck by the pivotal joint. In the neck, the Skull moves on the upper point of the neck bone in the position of left, right or up and down.

Hinge Joint

Hinge joints are like hinges in a door.
The hinge joints are joints between convex and concave bone surfaces that allow bones to move one way or the other. They are found on the fingers, toes, elbow, knee and ankle.

Fixed Joint

Such joints which do not allow bones to move are called fixed joints. For example – Upper jaw.

How do we know the shapes of the different bones in our body?

The answer is by looking at the X-ray image of the bones, we could know the shape of the bones.

Skeleton System and Bones

All the bones in our body combine together to form a framework to give a shape to our body. This framework is called the skeleton and the system is known as the skeletal system.
This system is made up of 206 bones and a few cartilages.
Around 300 bones are found in the body at the time of birth. By adulthood, certain bones fuse together and the number reduces to 206.
The human skeleton comprises the skull, vertebral column (backbone), ribs, chestbone, shoulder and hip bones and bones of hands and legs.

The number of bones found in these body parts are:

Name of the body parts	Total number of bones present
Skull	22
Ribs	24
Vertebral Column	33
In each hand	32
In each leg	30
Waist (hip)	02

Parts of the Skeletal System

The human skeleton system is classified into two main divisions:

Axial Skeleton: It includes – skull, vertebral column, sternum and ribs.
Appendicular skeleton: It includes – bones of limbs, shoulder and hip girdles.

Major bones found in our body

Some of the major bones of our body are:

Skull
Ribs
Vertical Columns
Pelvic bones
Shoulder bones

Skull

The skull protects our brain. The skull is composed of two sets of bones – cranial and facial. It is made up of 22 bones.

Ribs

Ribs protect important organs of our body i.e. heart & lungs.
Ribs have 12 pairs (total 24 bones) of bones.
Ribs connect chest bone and backbone together to form a box-like structure. This is called rib cage.

Vertical Column

The backbone is also known as the spine or vertebral column.
It is a bony structure that extends from the neck downwards to the back.
It is made up of many small bones called vertebrae. The vertebral column consists of 33 vertebrae.
The rib cage is joined to these columns. It serves as the main support for the body and protects the spinal cord.

Pelvic bones

It is also known as the hip bones.
The pelvic bones form the pelvic girdle. It supports the spine and connects with the lower limbs.
The pelvic girdle is formed by the fusion of three bones – Ilium, Ischium and Pubis.

Shoulder bones

The shoulder bone is formed by the collar bone and the shoulder blade.

Major functions of skeleton system and bones

The main functions of skeleton system/ bones are:

Support: It gives shape to our body. It also supports our body weight and helps us to stand straight.
Movement: It helps in body movements as well as in locomotion.
Protection: It protects the delicate organs of our body like skull protects brain, ribs protect heart and lungs.
Produces blood cells: Bones contain bone marrow where blood cells are produced.
Storage of minerals: Bones hold some minerals like calcium and phosphorous.

Muscles

Muscles are mainly involved in locomotory actions and changes in body posture.
Muscles work in pairs.
When one of them contracts, the bone is pulled in that direction. The other muscle of the pair relaxes.
To move the bone in the opposite direction, the relaxed muscle contracts to pull the bone towards its original position, while the first relaxes.
A muscle can only pull. It cannot push.

GAIT or Movement of Animals

Gait refers to a pattern of limbs actions that an animal uses repetitively during locomotion.
All animals have different types of gaits which differ based on the locomotory organs of the animals. The gait of some animals are discussed below:

Movement of Earthworm

Expansion and contractions of the muscles of earthworms help in movement.
During movement, the earthworm first extends the front part of the body, keeping the rear portion fixed to the ground. Then it fixes the front end and releases the rear end.
It then shortens the body and pulls the rear end forward. This makes the earthworm to move forward by a small distance.
Repeating such muscle expansions and contractions, the earthworm can move through the soil. Its body also secretes a slimy substance to help the movement.

Movement of Snail

Snails move by using a muscular foot that secretes mucus. This mucus reduces friction with the surface and allows the snail to glide forward in a wave-like motion.

Movement of Cockroach

Cockroach have three pairs of legs which help in walking.
The body is covered with a hard outer skeleton. This outer skeleton is made of a number of plates joined together and that permits movement.
There are also two pairs of wings that helps in flying.

Movement of Birds

Birds can fly as well as walk.
The birds can fly because their bodies are well suited for flying.
Their bones are hollow and light.
The bony parts of the forelimbs are modified as wings.
The breastbones are modified to hold muscles of flight which are used to move the wings up and down.
The bones of the hind limbs are typical for walking and perching.

Movement of Fish

Fish has a streamlined body i.e. the head and tail of the fish are smaller than the middle portion of the body – the body tapers at both ends.
During swimming, muscles make the front part of the body curve to one side and the tail part swings towards the opposite side. Then, quickly, the body and tail curve to the other side. This makes a jerk and pushes the body forward.
A series of such jerks make the fish to swim ahead.

Movement of Snake

Snake slithers and does not move in a straight line.
Snakes have a long backbone and many thin muscles.
The snake`s body curves into many loops. Each loop of the snake gives it a forward push by pressing against the ground.

Solution of the exercise

1. Fill in the blanks

a. Joints of the bones help in the …………………… of the body.

b. A combination of bones and cartilages forms the …………………….. of the body.

c. The bones at the elbow are joined by a ………………………….. joint.

d. The contraction of the …………………………… pulls the bones during movement.

Ans: 1

(a) movement

(b) skeleton

(d) muscles

2. Indicate true (T) and false (F) among the following sentences.

a. The movement and locomotion of all animals is exactly the same. ( )

b. The cartilages are harder than bones. ( )

c. The finger bones do not have joints. ( )

d. The fore arm has two bones. ( )

e. Cockroaches have an outer skeleton. ( )

Ans: 2

(a) false (F)

The movement and locomotion of all animals are different.

(b) false (F)

Cartilages are not as hard as bones and can be bent easily.

Finger bones also have joints.

(d) true (T)

Forearm has two bones. One is Ulna and the other one is radius.

(e) true (T)

Cockroaches have an outer skeleton which is also called an Exoskeleton.

3. Match the items in column I with one or more items of column II.

Column I	Column II
Upper Jaw	have fins on the body
Fish	has an outer skeleton
Ribs	can fly in the air
Snail	is an immovable joint
Cockroach	protect the heart
	shows very small movement
	have a streamlined body

Solution: 3

Column I	Column II
Upper Jaw	is an immovable joint
Fish	have fins on the body & have a streamlined body
Ribs	protect the heart
Snail	has an outer skeleton & shows very slow movement
Cockroach	can fly in the air & has an outer skeleton

4. Answer the following:

a. What is a ball and socket joint?

Ans:

A ball and socket joint is a synovial joint.
It is made up of two bones. The end of one bone is hemispherical, forming the ball, while the end of the other bone a cuplike depression, forming the socket.
The ball slides, rolls and spins within the socket to allow movement of the joint in multiple directions like:
Flex
Extend
Rotate
A back and forth motion
A circular motion
Hip joint and shoulder joint are examples of it.

b. Which of the skulls bone are moveable?

Ans. Only the lower jaw of the skull bone is moveable.

c. Why can our elbow not move backwards?

Ans. Our elbow has a hinge joint and hinge joint allows only back and forth movements. Hence, we cannot move our elbow backwards.

NCERT-Solutions-Class-6-Science-Body Movements