Question

Identify vertebrochondral ribs from the following.
a. All 12 pairs of ribs
b. 1st to 7th pairs of ribs
c. 8th, 9th, and 10th pairs of ribs
d. 11th and 12th pairs of ribs

Answer 1

Hint: Human skeleton i.e. mainly formed of bones and cartilages is divided into two main parts- axial skeleton and appendicular skeleton.
- Axial skeleton is along the longitudinal axis of the body and includes the skull, vertebral column, ribs and sternum.
- Appendicular skeleton includes the two types of girdles and limb bones that are along the transverse axes of the body.

Complete answer:
Ribs are the twelve pairs of thin and crescent-shaped bones that are present in the thorax. Each rib is posteriorly formed by a bony vertebral part and anteriorly by a cartilaginous sternal part. The bony part of each rib is double headed or bicephalous.

On the basis of sternal parts, the ribs are divided into three types:
- True or vertebra-sternal ribs: These are the first seven pairs of ribs whose sternal parts are directly attached to the sternum through the costal cartilages.
- False ribs: These are three pairs of ribs (8th, 9th, and 10th) pairs whose sternal parts are attached to that of the 7th pair of ribs and not to the sternum directly. So these are also called vertebra-chondral ribs.
- Floating ribs: These are the last two pairs of ribs (11th and 12th) whose sternal parts remain free.
In some Japanese tribes, the tenth rib is also floating and it is known as “Gorilla ribs”.

Hence, the correct answer is option (C).

Note: The ribs along with the thoracic vertebrae and sternum form the bony thoracic or rib basket to protect lungs and heart in thorax. The ribs also play an important role in respiration and floating ribs help in the protection of the kidney.