Ribs - Anatomy, Types, Function, Rib Cage and Diagram

What are Ribs?

Ribs Definition – The bony framework of the thoracic cavity is known as the ribs. They are flat, narrow and curved strips of bones that are found in all vertebrates. It is attached to the vertebrae dorsally, and ventrally to the breast bone (sternum) to form the rib cage.

Table of Contents

• Rib Structure (Anatomy)
• Types of Ribs
• Rib Cage – Human Body
• Functions of the Ribs
• Development of the Ribs
• Clinical Importance
• Frequently Asked Questions

Generally, there are twelve pairs of ribs found in humans. A typical rib anatomy has the following components – a costal groove, tubercle, neck, shaft and a head with two articular facets. The first, second, tenth, eleventh and twelfth ribs are somewhat an exception and differ slightly from the typical ribs.

The first rib has two costal grooves, one articular facet and is wide and short. The second rib is long and thin. The tenth rib consists of only once articular facet. And lastly, the eleventh and twelfth ribs have no neck and only one articular facet.

In a typical rib, one of the articular surfaces joins with the face of the vertebrae and the other with the transverse process of the vertebrae. The neck is a narrow area behind the head of the rib and the remainder is called the shaft.

The ribs attach to the thoracic vertebrae on the back and are numbered accordingly 1-12. For example, the first rib is attached to the first thoracic vertebrae (T1). On the front side, the ribs are attached to what is called a breastbone or a sternum by costal cartilage forming a sternocostal joint.

Based on the attachment to the sternum, there are three types of ribs –

• True Ribs: These ribs articulate directly with the sternum by costal cartilages. First to seventh ribs are true ribs. These ribs articulate with the sternum by forming a sternocostal joint.
• False Ribs: These ribs indirectly articulate with the sternum because their costal cartilages are attached to the costal cartilage of the seventh rib. Eight, ninth and tenth ribs are false ribs. These are also called vertebrochondral ribs.
• Floating Ribs: These ribs do not articulate with the sternum at any point. Eleventh and twelfth ribs are floating ribs.

In human body, the rib cage is a basket-like structure that is formed from the ribs and their corresponding attachments to the sternum and vertebral column. The rib cage structure houses two vital organs, the lungs and the heart and provides them with bony protection from outside injury and trauma.

The rib cage is expansible and semi-rigid in nature. The expansive property allows the cage to expand during activities such as breathing. The three false ribs and the two floating ribs help the cage to expand and also facilitates the movement of diaphragm for respiration.

• The thoracic cage protects the lungs and heart from any physical trauma and injury.
• The thoracic cage is separated from the lower abdomen by diaphragm. The expansion and contraction of the rib cage facilitates the process of respiration.

All ribs have attachments to vertebrae. The ribs and the vertebral column arise from the paired set of paraxial mesoderm called the somites. The somites differentiate into myotome, dermatome and sclerotome. The ribs and vertebrae develop from the sclerotome.

Ribs in Other Animals

In fish (jawed), there are two sets of ribs, the dorsal and ventral ribs. These ribs attach to the vertebral arches both upward and downward but are not attached in the front. Reptiles were the first organisms to show the attachment of ribs to the breastbone.

In snakes, the ribs are attached to all the vertebrae. But in mammals, the ribs are attached only to the thoracic vertebrae. The turtles have only 8 pairs of ribs and the amphibian frog has no ribs.

• The central ribs are more prone to cracking and fracture upon falling, facing accidents, gunshot wounds or any other such incident.
• Lifting heavy weights or objects can dislocate the ribs and can be extremely painful.
• Costochondritis is the inflammation of the costal cartilage (the connection between the ribs and sternum). It causes pain in the same amounts as caused during a heart attack.
• There are also chances of tumour development in the ribs that can be a primary or secondary lesion.

This was a brief note on the ribs. Stay tuned to BYJU’S for more important topics related to NEET.

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What are the 3 types of ribs in human body?

The thoracic cage has 12 pairs of ribs which can be classified into three types. The three types of ribs in human body are – True ribs, false ribs and floating ribs.

Which part of the body is called ribs?

In tetrapods, the chest portion or thorax is considered as the ribs.

Is there a difference between male and female rib cages?

The volume of female ribs is around 10% smaller than male ribs, according to a study. The reason still remains unclear.

Describe true ribs.

The first seven pairs of ribs are called true ribs. Here, the costal cartilage attaches ribs to the sternum.

What is the head of a rib?

Each rib has a head, shaft and neck. The end of the rib closest to the vertebra it articulates with is called the head.