Skeletal System
What is Skeleton System : The human skeleton is a framework of bones. An adult human has 206 bones of different sizes and shapes in his body .
Function of the Skeleton
The skeleton system is made of strong , hard and stuff bones . The main function of the skeleton system are as given below:
- The bones of the Skeleton from a body framework.
- They give shape and support to the body.
- They help us to stand upright.
- They protect the delicate internal organs.
- The bones are attached to muscles and help in movement.
Parts of the Skeleton
Our Skeleton consists of the skull , ribcage , spine or vertebrae and limbs.
Skull
The normal adult skull is made up of 22 bones. Eight flat bones are interlocked together.
They give shape to the head. Fourteen bones from the frame of the face.
The lower jaw is fixed to the upper jaw. We can move only the lower jaw of the skull. The skull protects the delicate brain . The skull has holes for eyes and nose. The nose do not have a bone. It is made of tough white tissues called cartilage. The jaw bones bear teeth. But remember , teeth are not bone.
Spine or vertebrae
The skull is attached to the spine or backbone , called the vertebrae.
The 33 bones of the vertebrae from the vertebral column. A spinal cord passes through this column. The spinal cord is a bundle of nerves. The vertebrae protects the delicate spinal cord.
Since the backbone is made up of many bones. We are able to bend and twist the backbone in different directions.
Ribcage
Twelve pairs of thin curved bones make the ribcage . They are attached to the backbone at the back and to the breast bone in the front. The last two pairs of ribs are not attached to the breast bone. They are called floating ribs.
The ribcage gives the protection to the lungs , heart and the kidneys.
Limbs – arms and legs
We have two pairs of limbs . Our arms are known as forelimbs and the legs are known as the hindlimbs.
Arms
The arm is made up of two Parts – the upper arm and the lower arm. They are joined together at elbows . The upper arm has one long bone. The lower arm has two bones.
The upper arm bone is joined to the spine with the help of shoulder bone or the pectoral girdle . The shoulder girdle is made up of a pair of shoulder blades and a pair of collar bones.
Legs
Like an arm , the legs is also made up of two Parts – the upper leg and the lower leg. They are joined together at the knees. The upper leg is the thigh . It has a single bone called femur. It is the longest bone in the body. At the knee , it is joined with two bones of the lower leg . The ankle and the toes have many small bones.
The thigh bone is attached to the hip bone , or the pelvic girdle.
Joints
Bones join together to form joints . Bones are held together by strong bands of fibre- like structure called ligaments. They control the amount of movement of bones.
At the joints , bones rub against each other , they are supported by a stuff but flexible substance called cartilage. The cartilage protects the bones from wear and tear dur to friction.
There are two main types of joints
- Movable Joints
Joints which help in movements are called movable Joints.
Example : arms , legs
- Immovable Joints
Joints that cannot be moved .
Example : the joints of skull , the joints between the ribcage and breast bone.
