Ribs

The curved bones that form the rib cage, providing structure and protection to the thoracic organs.

Ribs are long, slender bones that articulate with the thoracic vertebrae at the back and curve around to the front of the chest. They are primarily composed of bone tissue, though their cartilaginous ends allow flexibility. Humans typically have 24 ribs, arranged in 12 pairs. The first seven pairs, known as true ribs, directly connect to the sternum via costal cartilage, while the next three pairs, called false ribs, connect to the sternum indirectly. The last two pairs are referred to as floating ribs, as they do not connect to the sternum at all.

Terminologia Anatomica

costa

System

Skeletal system

Function

The ribs primarily serve to protect vital organs located in the thoracic cavity, such as the heart and lungs, from physical trauma. This bony structure also plays a crucial role in respiration. During inhalation, the muscles between the ribs, called intercostal muscles, contract to elevate the ribs and expand the chest cavity. This expansion lowers the internal air pressure, encouraging air to flow into the lungs. Conversely, during exhalation, the ribs descend, assisting in pushing air out of the lungs. Their arrangement also helps maintain the shape of the thoracic cavity, supporting overall posture and movement.

Location

The ribs are located surrounding the thoracic cavity, extending from the spine in the back toward the sternum at the front. Each rib is positioned in a sloping manner, radiating laterally and then anteriorly. They articulate with both the thoracic vertebrae, allowing for a degree of mobility, and with the costal cartilage, which connects them to the sternum. This arrangement creates the rib cage, a protective framework that encases the thoracic organs while allowing the necessary expansion and contraction during respiration.

Did You Know?

Ribs can vary slightly among individuals; some people may have an extra rib (known as a cervical rib) or one less than the typical 24.
Ribs not only protect organs but also support the upper body and play a role in the biomechanics of breathing.
The floating ribs do not attach to the sternum or to any other ribs, highlighting the variety in rib structure.
Rib fractures are common injuries that can lead to severe complications, highlighting their protective role.