Problem 24 - Anatomy and Physiology of Animals

Question

True ribs are _____. a. ribs \(8-12\) b. attached via their costal cartilage to the next higher rib c. made entirely of bone, and thus do not have a costal cartilage d. attached via their costal cartilage directly to the sternum

Step-by-Step Solution

Answer

True ribs are attached via their costal cartilage directly to the sternum (option d).

Step 1: Understanding the Term 'True Ribs'

The human rib cage consists of 12 pairs of ribs, which are classified into true ribs, false ribs, and floating ribs. It is important to understand how true ribs are defined. True ribs are specifically the ribs that are directly attached to the sternum via their own costal cartilage.

Step 2: Analyzing Each Option

We have four options to consider: - a. states that true ribs are ribs 8-12. - b. states that they are attached via their costal cartilage to the next higher rib. - c. states they are made entirely of bone and don't have costal cartilage. - d. states they are attached directly to the sternum via their costal cartilage.

Step 3: Evaluating Option (a)

Option (a) suggests true ribs are ribs 8-12. However, true ribs are specifically ribs 1-7 because these are directly attached to the sternum with their own costal cartilage, not ribs 8-12.

Step 4: Evaluating Option (b)

Option (b) suggests true ribs are attached to the next higher rib via their costal cartilage. This describes false ribs rather than true ribs, as false ribs attach indirectly to the sternum.

Step 5: Evaluating Option (c)

Option (c) states true ribs are made entirely of bone and lack costal cartilage. This is incorrect; true ribs have an integral costal cartilage connection to the sternum.

Step 6: Evaluating Option (d)

Option (d) states true ribs are attached via their costal cartilage directly to the sternum, which accurately describes the property of true ribs (ribs 1-7).

Step 7: Conclusion

Comparing all options, option (d) is the correct definition of true ribs as those directly attached to the sternum with their costal cartilage.

Key Concepts

True Ribs

In the human body, we have 12 pairs of ribs that form the rib cage, which encases our lungs and some other vital organs. These ribs are divided into three classifications: true ribs, false ribs, and floating ribs. We are focusing on the true ribs here. These are the first 7 pairs of ribs, numbered 1 to 7, which are directly anchored to the sternum, the central bone in our chest, via their individual costal cartilages. This direct attachment is what distinguishes them as "true" ribs. While ribs 8 through 12 are not considered true ribs, their function remains crucial for respiratory movement and protection of internal organs.

Costal Cartilage

Costal cartilage plays a critical role in the anatomy of the rib cage. It is a flexible, cartilaginous strip that connects the ribs to the sternum. For true ribs, which are ribs 1 through 7, each rib pair has its own costal cartilage. This structure aids in providing both protection and mobility. The cartilage allows the rib cage to expand and contract, which is essential for effective breathing. Additionally, the costal cartilage provides the necessary resilience and elasticity needed to safeguard vital organs like the heart and lungs from potential shocks or impacts.

Sternum Connection

The sternum, also known as the breastbone, serves as the central point of attachment for the true ribs, specifically ribs 1 to 7. This bone is flat and located in the center of the chest, forming the front portion of the rib cage. The connection between the true ribs and the sternum is made possible through the costal cartilages.

• This direct sternum connection offers tremendous stability and strength to the rib cage.
• It also supports upper body movement while maintaining protection for the thoracic organs.

The structure of the sternum includes three parts: the manubrium at the top, the body in the center, and the xiphoid process at the bottom, all of which help facilitate this vital connection.