THE SKELETAL SYSTEM

the human body is a fascinating machine. just as a machine is made of many parts , our body is made up of many organs each organs has a specific function to perform. for example: Eyes are used for seeing , legs for walking etc.

some of the organs system in our body are the digestive system .respiratory systems,circulatory system , nervous system, Excretory system, skeletal system and the reproductive system.

the human body is made up of many organ system . all these system work in close coordination with one another . look at the picture given to learn about the main organ system of our body .
you will learn more about these system in higher classes . however , in this unit we shall only study the skeletal nervous and respiratory system in detail .

THE SKELETAL SYSTEM

the skeletal system is the framework of bones that imparts shape and support to our body . without the skeletal system our body will simply collapse like a pack of cards.
the skeletal system consists of all the bones in the body and the joint.
our body has bones of different sizes and shapes. all these bones are joined together. this is termed the skeletal system. observe carefully the picture given alongside. it shown the different parts of the human skeleton.

the boney framework of the body is called the skeleton.

 Functions of the skeletal system
1:The skeleton forms a strong framework which support the body.
2:Together with the muscles and joints, it help the movement of the body.
3: many parts of the skeleton enclose and protect important organs such as:- skull,protects the brain._vertebral column protect the spinal cord.

THE SKULL

try knocking your head with with your index finger . the sharp ,boney sound you here is produced by the skull. the skull. the skull is outer boney protective cover of the brain.

DO YOU KNOW 
The human skeleton is made up of 206 bones. the skull is made of 28 bones.
The skull consist of to parts.
(i). the brain box which forms the head.
(ii). the facial bones which import shape to the face.
FUNCTION OF THE SKULL
•the skull protects the brain
•the upper jaw (maxilla) and the lower jaw  (mandible)have sockets for our teeth
•teeth are hard bone like structures in both the jaws.
•the upper jaw is immovable
• the lower jaw is the only boney part of the skull (face) that moves . all other bones in our skull are fixed.
•the jaws contain the teeth for biting and chewing and also help us the talking.

The Backbone

the spinal cord is protected by the backbone. it is made up of a series of small bones called vertebrae
Run your hand along the central portion of your back . you can feel your backbone. you can also feel the small bones , the vertebrae . the column of the backbone is called the vertebrae column.

     DO YOU KNOW
the human backbones is made up of 33 bones called vertebrae. 

The RIB CAGE

• Ribs make a cage of bones around the chest called the rib cage.
• the bone in the middle of the rib cage is called the BREASTBONE OR STERNUM. the long curved bones attached to it are called the RIBS. 
• all the 12 pairs of ribs are jointed at the back to the backbones but only the first 10 pairs are joint in front to the breastbone . 
•this is why the last two pairs are called FLOATING RIBS.
• the rib cage is formed by the ribs the vertebral column and the breastbone.
                  
              The limbs

we have two pairs limbs:
the forelimbs the arms and the hind limbs (the legs)
there is only one bone called the humerus in the upper arm and two bones in the fore arm. the bone in the thing is called the femur,the longest bone in our body.


Joints
a joint is the place where two bones meet  joints help the bones to move which in turn cause the body part to move there are two many types of joints. 

                                    JOINTS
1:MOVABLE JOINTS
2:IMMOVABLE JOINTS

MOVABLE JOINTS  : joint on the shoulder ,wrist,ankle,and knees are example of movable joint

IMMOVABLE JOINT  : joints like the ones in your skills except the lower jaw and between the ribs and the breast bone are example of immovable joints.


HINGE JOINTS
this joint works like  the hinges in the door. it allows only back and forth movement. e. g bones in the knee elbow , fingers and toes.

PIVOT JOINTS
This type of joint is found where the skull meet the first vertebra. it allows the head to move up and down and sideways.

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