Nursing School Knowledge: The Ribs' Anatomy

Pop quiz: How many ribs does the average human adult have?

1. 12
2. 24
3. 36

If you answered B, congratulations!

You’re correct, 24 ribs. The average human adult has 12 pairs of ribs.

However, did you know that not everyone is born with the same number of ribs?

Some individuals may have an extra rib, known as a cervical rib. Or they may be born with one less rib on one side.

This natural variation is normal and doesn’t affect a person’s health.

Now that you know the number of ribs in the human body, let’s dive deeper into the ribs’ anatomy.

An overview of the ribs’ anatomy

The rib cage is a protective fortress for vital organs, such as the heart and lungs, which also provide specific landmarks for health care professionals.

Let’s break it down into key components.

True ribs vs. false ribs: Unraveling the distinction

The rib cage is comprised of 12 pairs of ribs, each contributing to the structural integrity of the chest cavity.

There are two types of ribs: true and false.

• True Ribs (1-7): True ribs attach to the sternum by costal cartilage, forming a direct and solid connection. True ribs protect the thoracic organs and maintain the chest’s structural stability.
• False Ribs (8-12): The false ribs don’t have a direct attachment to the sternum. Ribs 8-10 attach to the costal cartilage of the rib above. Ribs 11 and 12, often called floating ribs, lack a sternal attachment.

Intercostal muscles: The unsung heroes of breathing

There are 11 intercostal spaces in the thoracic cavity, filled with arteries, lymph nodes, muscles, and veins.

The intercostal muscles run between the ribs, which is pivotal in respiration. These muscles aid in expanding and contracting the chest cavity, allowing for efficient breathing.

The three layers of intercostal muscles are:

• External: These muscles aid inhalation by elevating the ribs.

• Internal: These muscles help with exhalation by pulling the ribs down.
• Innermost: These are the deepest layer of intercostal muscles, aiding inhalation and exhalation.

Typical and atypical rib bones

Individual rib bones have different structures and functions, depending on their location in the ribcage.

Typical ribs

Ribs 3-9 are typical ribs and consist of the following components:

• Anterior extremity: Known as the costal cartilage, this part attaches the rib bones to the sternum.
• Body (shaft): The body of the rib is flat, long and curved near its posterior end, forming a costal angle. A costal groove extends along each rib’s inferior (bottom), housing nerves and blood vessels.
• Head: The head of the rib connects to the vertebrae, serving as a point of articulation.
• Neck: This small portion connects the head with the rest of the rib.
• Tubercle: A small bump on the posterior side of ribs 6-10, serving as an attachment point for muscles.

Atypical ribs

The remaining ribs (1, 2, 10-12) are atypical because they have unique structures and functions compared to typical ribs.

These include:

• Rib 1: This is the shortest and broadest of all the ribs, protecting blood vessels and nerves.

• Rib 2: Like the first rib, it protects vital blood vessels and nerves.

• Rib 10: This rib only has a single side on its head, instead of the usual two found on typical ribs.

• Rib 11 and 12: These are also unique as they don’t have necks or tubercles. Their shafts are also shorter than other rib bones.

Understanding the differences between typical and atypical ribs is important in diagnosing and treating rib injuries or deformities. For example, fractures in atypical ribs may require different treatment methods because of their unique structures.

Knowing the location and function of specific rib bones can help address muscle imbalances or postural issues. For instance, a small bump on the posterior side of ribs 6-10 is an attachment point for muscles and can help determine which muscles may be overactive or underactive.

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