Out of 'X' pairs of ribs in humans only 'Y' pairs are true ribs. Select the option that correctly represents values of X and Y and provides their explanation.
- X = 12, Y = 5; True ribs are attached dorsally to vertebral column and sternum on the two ends
- X = 24, Y = 2; The true ribs are dorsally attached to vertebral column but are free on ventral side
- X = 24, Y = 12; True ribs are dorsally attached to vertebral column but are free on ventral side
- X = 12, Y = 7; True ribs are attached dorsally to vertebral column and ventrally to the sternum
Answer
(4) X = 12, Y = 7; True ribs are attached dorsally to vertebral column and ventrally to the sternum
Solution
As per NCERT, there are 12 pairs of ribs ⇒ X = 12.
The first seven pairs are called true ribs; dorsally they are attached to the thoracic vertebrae and ventrally connected to the sternum with the help of hyaline cartilage ⇒ Y = 7.
Answer: (4)