SCIENCE - WIN POINT ... parts of our body. There are 206 bones in the human skeleton. The bones of...
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1. SKELETON (Framework of Bones)
The ability of a human being (or an animal) to move its body from one place to another is called locomotion. Human beings show two types of body movements: Movements of the body parts (like mouth, head, backbone, arms,
hands, legs and foot, etc.), and Movement of the whole body from one place to another (which is
The bony framework inside our body is called skeleton. In human beings, the skeleton is inside the body, so it is called an ‘endoskeleton’. Skeleton is called ‘kankal’ in Hindi.
The bones of skeleton provide a framework which holds our body together. The skeleton also gives a shape to our body. The human skeleton is made mostly of bones with some cartilage in certain parts. Bones are hard and tough but cartilage is softer than bones. 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. The bones of skeleton are interconnected through joints to form various parts of our body. 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.
1.1 Description of Skeleton
The skeleton consists of : Skull, Backbone, Ribs, Breastbone, Shoulder bones, Hip bone, Arm bones and Leg bones. The human skeleton consists of a strong backbone which has skull at its top end. The skull has eye
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sockets, an upper jaw, and a lower jaw in it. Ribs are attached to the upper part of backbone forming a rib cage. There is a breastbone called sternum in front of the rib cage. At the lower end of backbone is a wide and strong structure called hip bone. Just below the neck, there are shoulder bones on both the sides of the skeleton. The shoulder bones consist of two bones: Collar bone and shoulder blade. The scientific name of collar bone is clavicle and that of shoulder blade is scapula.
The upper limb of human body from the shoulder to the hand is called an arm. There are two arms in the human skeleton. The two arms are attached to the two shoulder blades of the skeleton by ball and socket joints. 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 lower limbs of the body on which a person walks or 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. The upper leg consists
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of a single bone called femur. Femur is commonly known as thigh bone. The lower leg is from knee to ankle. The lower leg consists of two bones: tibia and fibula. The foot consists of various types of small bones which form ankle, middle part of foot and toes.
1.2 Functions of Skeleton
The important functions of skeleton are as follows: (a) Skeleton holds the whole body together and gives it a shape. (b) Skeleton protects many delicate internal organs of the body from
outside damage. (c) Skeleton provides numerous points for the attachment of muscles of
the body. (d) Alongwith muscles, skeleton helps in the movement of body parts
The 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 a strong case around the brain. In this way, skull protects the brain. The lower part of skull contains the face bones (including nose bone). Our face has sense organs like eyes, ears and nose.
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Some of the main functions of the skull are as follows: Skull protects the brain. Skull protects the sense organs of the face Skull gives shape to our head.
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 (or skeleton). Backbone is made up of 33small 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 (soft bones). These discs allow the vertebrae to move slightly and enable the backbone to bend forwards and backwards (or from side to side). Our backbone supports the head at its top. The shoulder bones, rib bones and hip bone 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.
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The main functions of backbone are as follows: (a) Backbone provides main support to the body. (b) Backbone supports the head at its top. (c) Backbone attaches shoulder bones, ribs and hip bone. (d) Backbone protects the spinal cord.
1.5 Rib Cage
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’. Some of the important internal organs of our body such as heart, lungs and liver lie inside the strong bony rib cage. The rib cage protects the delicate internal organs like heart, lungs and liver. The rib cage also takes part in our breathing movements.
The main functions of the rib cage are the following:
Rib cage protects the internal organs of the body such as heart, lungs and liver.
Rib cage takes part in our breathing movements.
1.6 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 bone and shoulder blade. The collar bone is a
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long, curved bone. Collar bone keeps the shoulders apart. The shoulder blade is a large and flat triangular bone. The upper arm fits into the socket of shoulder blade forming ball and socket joint. The main functions of the shoulder bones are the following:
(a) Collar bones on the two sides of the neck keep our shoulders apart.
(b) Shoulder blades attach the arms to our body. (c) Shoulder blades provide sites for muscle attachments which move
the arms, neck and upper part of our body.
1.7 Hip Bone (Pelvic Bone)
The hip bone forms a large, basin-shaped frame at the lower end of the backbone, to which the legs are attached. The hip bone is also known as pelvic bone. Hip bone is not a single bone. It is made up of a number of
bones fused together by fixed joints. The hip bone encloses the portion of our body below the stomach. The thigh bones of our legs are joined to the hip bone by the ball and socket joints. Actually, hip bone forms the link between upper part of our body and the legs.
The important functions of the hip bone are as follows: (i) Hip bone supports and protects the lower organs of the body such as
intestines, urinary bladder and internal sex organs. (ii) Hip bone attaches the legs to our body. (iii) Hip bone provides sites for the attachment of muscles that move
legs, hips and trunk.
1.8 Bones of the Hand
Our hand is made up of three parts: wrist, palm and fingers. The wrist consists of 8 small bones known as carpals. The wrist
bones form movable joint with the bones of forearm. The palm of hand is composed of 5 longer bones called metacarpals.
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The fingers are made of jointed bones called phalanges. There are 3 bones in each finger but the thumb has only 2 bones.
Most of the skeleton consists of hard bones. However, at some places in the skeleton there is a material which is not as hard as bones and which can be bent. It is called cartilage. Cartilage is a firm but flexible material found at some places in the skeleton. Cartilage is much softer than bone. Cartilage can be bent without breaking. In fact, cartilage is a kind of softer and elastic bone. Cartilage is present in the following places in our body:
(a) Cartilage is present in the pinnae of ears. (b) Cartilage is found at the end of nose. (c) Cartilage is found on the end of bones where they meet one another
at a joint. (d) Cartilage is also present between the vertebrae of backbone.
Upper part of ear has cartilage The ear lobe The upper part of our ear is called pinna and the lower part is called ear lobe. Cartilage gives support and shape to the ear. Cartilage is flexible that is why we can bend the pinna of our ear quite freely, without the danger of breaking. It is the presence of cartilage which gives support and shape to our nose and ears. Cartilage is also found on the ends of bones where they meet one another at a joint. Cartilage is smooth. The layer of smooth cartilage reduces friction a