Page 2 - 2. Lesson Notes-Structure of skeleton

• The curved bones in our chest are called ribs.
• There are 12 pair of ribs (24 bones) forming a cage-like structure called the rib
cage.
• The ribs are flat, thin and curved bones.
• The ribs are-
❖ Joined with the backbone at the back
❖ Joined with breastbone in the front
TH
• The last two pairs (11 & 12 TH pair) of ribs are not attached in front and are
hence called the floating ribs.
• Ribs protect the heart, lungs, stomach, and kidneys.

THE BACKBONE OR SPINE

• The backbone is a long, hard, and uneven structure on our back.
• It is also known as the spine or vertebral column.
• It runs from the base of the skull to the lower back.
• It forms the central supporting rod for the skeleton.
• It is made up of 33 small bones called vertebrae(singular-vertebra).
• These vertebrae are joined to each other.
• It is because of these joints that we can bend and twist our back.
• Each vertebra has a hole through it.
• The spinal cord passes through these holes.
• Animals those have vertebral column are called vertebrates-example fish,
amphibians, reptiles, birds, and mammals.
• Animals those who don’t have vertebral column are called invertebrates-example
ants, earthworms, starfish, snails etc.

THE LIMBS

• Limbs allow us to perform various types of movements.
• We have two pairs of limbs-

❖ The fore limbs-arms
❖ The hind limbs- legs

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