Costal cartilage connects the ribs to the sternum, or breastbone. These structures are composed of hyaline cartilage and are found at the forward ends of the ribs. This arrangement forms a semi-rigid yet flexible connection integral to the thoracic cage’s structure.
Anatomy and Function of Costal Cartilage
The first seven pairs of ribs connect directly to the sternum through their costal cartilages. The subsequent three pairs—the eighth, ninth, and tenth ribs—have cartilages that connect to the cartilage of the rib above them. The final two pairs of ribs, the eleventh and twelfth, have cartilage tips that do not connect to the sternum and end within the abdominal musculature.
The flexible nature of hyaline cartilage gives the thoracic cage elasticity. This allows the rib cage to expand during inhalation and contract during exhalation. The costal cartilages provide the structural mobility required for these changes in chest volume.
Common Conditions Affecting Costal Cartilage
One of the most frequent issues involving this tissue is costochondritis, an inflammation of the cartilage where a rib attaches to the sternum. This condition causes sharp pain in the chest wall, which can be mistaken for more serious cardiac problems. The exact cause of costochondritis is often not clear, but it can be associated with physical strain or illness. Costochondritis does not involve swelling.
Another condition, Tietze’s syndrome, is also an inflammatory disorder but is distinguished by the presence of localized swelling at the cartilage connection, affecting one of the upper four ribs. The pain from Tietze’s syndrome can appear suddenly and may radiate to the arm or shoulder. Direct physical trauma can also cause fractures or separations of the costal cartilage. Management for these conditions often involves rest, ice or heat, and anti-inflammatory medications to reduce pain and inflammation.
The Healing Process
Recovery from costal cartilage injuries is notably slow due to the biological nature of the tissue itself. Cartilage is avascular, meaning it does not have its own blood vessels to supply it with nutrients and oxygen. Instead of a direct blood supply, cartilage receives nourishment through a slow process of diffusion from surrounding tissues. This is a significant contrast to bone, which is highly vascularized and can heal much more efficiently.
The lack of direct blood flow severely limits the body’s ability to repair damaged cartilage. Reparative cells and the substances needed for tissue regeneration cannot reach the injury site quickly or in large quantities. Consequently, healing is often incomplete, sometimes resulting in the formation of fibrous scar tissue rather than new cartilage. This biological limitation underscores why patience and strict avoidance of activities that stress the chest wall are necessary for recovery from costal cartilage injuries.