Question

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

• A. X=12, Y=7, True ribs are attached dorsally to the vertebral column and ventrally to the sternum
• B. X=12, Y=5, True ribs are attached dorsally to the vertebral column and sternum on the two ends
• C. X=24, Y=7, True ribs are dorsally attached to vertebral column but are free on ventral side
• D. X=24, Y=12, True ribs are dorsally attached to vertebral column but are free on ventral side

Answer 1

The correct option is A

X=12, Y=7, True ribs are attached dorsally to the vertebral column and ventrally to the sternum

The correct option is option A:

Explanation for Correct option:

1. True ribs are the first seven ribs (vertebrosternal ribs).
2. Each of these ribs' costal cartilage connects directly to the sternum.
3. The ribs 8–12 are known as false ribs (vertebrochondral ribs).
4. These ribs' costal cartilages do not connect directly to the sternum.
5. The first seven pairs of ribs are true ribs, the eighth, ninth, and tenth pairs are false ribs, and the eleventh and twelfth pairs are floating ribs.
6. False ribs are attached to the 7th ribs by hyaline cartilage and are attached dorsally to the vertebral column and ventrally to the sternum, whereas true ribs are attached dorsally to the vertebral column and ventrally to the sternum.
7. Ventrally, floating ribs are not attached.

Final answer:
In humans, there are 12 pairs of ribs, with 7 pairs (first to seventh) linked dorsally to the vertebral column and ventrally to the sternum. The option that correctly represents values of X and Y and provides their explanation is “ X=12, Y=7, True ribs are attached dorsally to the vertebral column and ventrally to the sternum”.