Skeleton: Framework of Bones

Question 1 What is skeleton. What are the various functions of skeleton?

Question 2 What is backbone. Write the main functions of backbone?

Question 3 Define the term locomotion? Name 2 types of body movements?

Question 4 What are the various parts of skeleton?

Question 5 Draw a labelled diagram of skull and hand showing bones present in it.

Question 6 What are the main functions of skull?

Question 7 What is a rib cage? State the function of it?

Question 8 Name the two shoulder bones. Write the functions of shoulder bones?

Question 9 What is cartilage? Name the body parts where cartilage is found?

Question 10 What is the name of small bones which make up backbone?

Question 11 What are the functions of hip bones?

Question 12 What are carpels, meta carpels and phalanges?

Also Read  NCERT Solutions for Chapter 8 Body Movements

 

Locomotion

The ability of a human being to move its body from one place to another is called locomotion.

Human beings show two types of body movement:

(1) Movements of the body parts like mouth, head, backbone, arms, legs, foot etc.

(2) Movement of the whole body from one place to another.

Skeleton

The hard structures inside our body are the bones. The bony framework inside our body is called skeleton. In human beings, the Skeleton is inside the body, so it is called as endoskeleton.

The bones of skeleton provides a framework which holds our body together.

The skeleton also gives a shape to our body.

The Skeleton is made of bones of many different shapes and sizes.

The X-ray images show the shape and number of bones in the various parts of our body. There are 206 bones in the human skeleton. Our skeleton has movable joints between various bones which allow the muscles to move the head, shoulders, arms, legs and other parts of the body.

 

The Skeleton consists of skull, backbone, ribs, breastbone, shoulder, bones, hip bone, arm bone and leg bones.

(1) The human skeleton consist of a strong backbone which has skull at its top end. The skull has two eyes sockets, upper jaw and lower jaw in it.

(2) Ribs are attached to the upper part of the back bone forming a rib cage. There is a breastbone in front of the rib cage.

(3) At the lower end of backbone is a wide and strong structure called hip bone.

(4) Just below the neck, there are shoulder bones on both sides of the skeleton. The shoulder bones consists of two bones : collar bones and Shoulder blade. The scientific name of collar bone is clavicle and that of shoulder blade is scapula.

(5) The upper limb of human body from the shoulder to the hand is called an arm. There are two arms in human skeleton. The two arms are attached to the shoulder Blades of the skeleton by ball and socket joints. Each arm consists of three parts: upper arm, lower arm and hand. The upper arm is from shoulder to elbow. The upper arm consists of a single bone called humerus. The lower arm is from elbow to wrist. The lower arm is made up of two bones: radius and ulna. The upper arm bone is connected to lower arm bones by a hinge joint at the elbow. The hand consists of various small bones which form wrist, palm and fingers.

(6) The lower limbs of the body on which person walks on stands are called legs. There are two legs in the human body. The two legs are attached to hip bone of the skeleton by ball and socket joints. Each leg consists of three parts: upper leg, lower leg and foot. The upper leg is from hip to knee. The upper leg consists of a single bone called femur or thigh bone. The lower leg is from knee to ankle. The lower leg consists of two bones: tibia and fibula. The upper leg bone is connected to the lower leg bones at the knee by a hinge joint. There is also a knee cap called patella. The foot consist of various types of small bones which form ankle, middle part of foot and toes.

 

Functions of Skeleton

(1) Skeleton holds the whole body together and gives it a shape.

(2) Skeleton protects many delicate internal organs of the body from outside damage.

(3) Skeleton provides numerous points for the attachment of muscles of the body.

(4) Along with muscles 10 helps in the movement of body parts and locomotion.

Skull

Bony part of our head is called skull. The skull is made of 22 bony plates joined together.

Our brain is inside the skull in its upper part. The brain is made of soft tissue which could be easily damaged without a hard covering. The bones of skull form of strong case around the brain. In this way, skull protects the brain. The lower part of skull contains the face bones. Our face has sense organs such as eyes, ears, nose.  The eyes are contained in two large cavities called eye sockets in front of the skull.

The main functions of skull are:

(1) Skull protects the brain.

(2) Skull protects the sense organs of the face.

(3) Skull give shape to our head.

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.

The backbone forms the main supporting structure of the body. Backbone is made up of 33 small bones placed one over the other. The small bones which make up the backbone are called vertebrae. Between the various vertebrae of backbone are the discs of cartilage i.e. soft bones. These discs allow the vertebrae to move slightly and enable the backbone to bend forward and backward. Top 7 vertebra of backbone form our neck.

Our backbone supports the head at its top. The shoulder bones, rib bones and hip bones, are all joined to the backbone. Each vertebra has a hole in it. Due to this, there is a hollow centre inside the backbone. The spinal cord passes inside the hollow cavity of the backbone. Thus backbone encloses and protects the spinal cord from damage.

Functions of backbone

(1) Backbone provides main support to the body.

(2) Back bone supports the head at top.

(3) Backbone attaches shoulder bones ribs and hip bone.

(4) Backbone protects the spinal cord

 

Rib cage

Chest bones are called ribs. Ribs are curved bones in our chest.

There are 12 pairs of ribs in the chest of our body. There is a long back bone at the back of our body. There is also a small bones called breast bone in the chest region, in front of our body. One end of all ribs is joined to the backbone and their other end is joined to the breast bone. All the rib bones, a part of backbone and the breastbone join to form a bony cage or box like structure.

The hollow, bony structures formed by the ribs is called rib cage. Internal organs of our body such as heart, lungs, liver lie inside the strong bony rib cage. The rib cage protects the delicate internal organs like heart, liver and lungs. The rib cage also take part in our breathing movement.

Shoulder bones

Shoulders are that part of the body to which our arms are attached. The human body has two shoulders one on each side of the neck.

There are two shoulder bones : collar bones and Shoulder blade. The collar bone is a long curved, bone. One end of the collar bone is attached to the shoulder blade and the other end of collar bone is fixed  to the breastbone of rib cage.

Collar bone keeps the shoulder apart. The shoulder blade is a large and flat triangular bone. The shoulder blade is attached to backbone by muscles to allow the free movement of the shoulder. Each shoulder blade has a cup shaped socket. The upper arm fits into the socket of  shoulder blade forming ball and socket joint.

The main functions of shoulder bone are :

(1) Collar bone on the two sides of the next keep our shoulders apart.

(2) Shoulder blades attached the arm to our body.

(3) Shoulder blade provide sites for muscle attachment which move the arm, neck and upper part of our body.

 

Hip bone

The hip bone forms a large, basin shape framework at the lower end of the backbone, to which the legs are attached. The hip bone is also known as pelvic bone. It is made up of number of bones fused together by fixed joints. The hip bone encloses the portion of our body below the stomach. The hip bones has two sockets on the two sides of its lower part. The thigh bone of our legs are joined to the hip bone by the ball and socket joint.

Hip bone forms the link between upper part of our body and the legs.

Functions of hip bones

(1) Hip bone support and protects the lower organs of the body such as intestine, urinary bladder and sex organs.

(2) Hip bone attaches legs to our body.

(3) Hip bone provides sites for the attachment of muscles that move legs, hips and trunk.

Bones of the head

Our hand is made up of three parts:  wrist, palm and fingers.

The wrist consists of 8 small bones known as carpels. The palm of hand is composed of five long bones called metacarpals. The fingers are made of joined bones called phalanges. There are three bones in each finger but the thumb has two bones.

The wrist bones form movable joints with the bone of forearm. Due to this wrist is flexible. The finger bones form movable joints among themselves.

Cartilage

At some places in the Skeleton there is a material which is not as hard as bones and which can be bend. It is called cartilage.

Cartilage is a firm but flexible material found at some places in the skeleton. Cartilage can bend without breaking. Cartilage is a kind of software and elastic bone.

(1) Cartilage is present in the pinna of ear.

(2) Cartilage is found at the end of nose.

(3) Cartilage is found on the end of bones where they meet one another at a joint.

(4) Cartilage is also present between the vertebrae of backbone.

The pinna of our ear contains cartilage. It gives support and shape to the ear. It is flexible that is why we can bend the pinna of our ear quite freely, without the danger of breaking.

We can bend the nose easily. There is a cartilage in the end of our nose. It is the presence of cartilage which gives support and shape to our nose.

The layer of smooth cartilage reduces friction and allows the ends of bones to move easily over each other without damaging them. Cartilage is found in the joints of our body. The presence of cartilage discs between vertebra makes the backbone flexible so that it can bend absorbs the shock when we run, jump or do other such activities.

Notes for Chapter 8 Body Movements Skeleton: Framework of Bones Joints of Body Muscle Contraction and Movement in Animals