Question

How many ribs are present in human beings? (a) 6 pairs (b) 9 pairs (c) 12 pairs (d) 15 pairs

Short answer

The correct answer is (c) 12 pairs.

Step-by-step solution

Identify the correct answer

There are 12 pairs of ribs in the human body, making a total of 24 ribs. This includes 7 pairs of 'true' ribs which are directly attached to the sternum, 3 pairs of 'false' ribs which are indirectly attached to the sternum, and 2 pairs of 'floating' ribs which have no sternum attachment.

Key concepts

True Ribs

In the human rib cage, the first seven pairs of ribs are known as true ribs. This is because each pair is directly connected to the sternum, which is a long, flat bone located in the center of the chest. The connection to the sternum is made possible by costal cartilages. This direct attachment provides a sturdy protective frame around important organs such as the heart and lungs. - These ribs are labeled as ribs 1 through 7. - They play a crucial role in maintaining the structure and integrity of the thoracic cavity. - Due to their firm attachment, they help in the overall support and protection of upper body organs. True ribs are essential for maintaining the proper functioning of the respiratory system, as their movement assists in the expansion and contraction of the chest cavity during breathing.

False Ribs

Following the true ribs, the next three pairs (ribs 8, 9, and 10) are termed as false ribs. These ribs are not attached directly to the sternum. Instead, they are connected to the sternum indirectly through the cartilage of the rib pair above them, creating a more flexible structure. - Referred to as ribs 8 through 10. - Their indirect attachment allows for a greater range of motion in the rib cage. - This flexibility helps accommodate movements such as twisting and bending. Although they are not as rigid as true ribs, false ribs still play a supportive role in protecting the internal organs of the thorax, such as parts of the liver and spleen.

Floating Ribs

The last two pairs of ribs in the human rib cage are known as floating ribs. These are uniquely named because they do not have any attachment to the sternum whatsoever. Instead, their ends are free, thus appearing to "float." - Floating ribs are ribs 11 and 12. - They are shorter and more elastic compared to the other ribs. - The lack of sternum attachment gives them a notable role in our body's flexibility. Floating ribs serve the function of protecting the kidneys and part of the back, while also allowing a significant extension of movement. They are vital for movements that require bending at the waist or twisting the torso.