ribcartilage

Rib cartilage, or costal cartilage, is hyaline cartilage that joins the anterior ends of the ribs to the sternum or to adjacent costal cartilages. It extends from the first through the tenth rib, with ribs 1–7 articulating directly with the sternum (true ribs), ribs 8–10 attaching to the cartilage of the rib above (false ribs), and ribs 11–12 whose costal cartilages do not reach the sternum (floating ribs).

Structure and histology

Costal cartilage is composed of hyaline cartilage characterized by chondrocytes in lacunae within an extracellular matrix rich in type II collagen and proteoglycans. The tissue is typically surrounded by a perichondrium, which supplies blood and progenitor cells for repair. The cartilage is relatively flexible, allowing it to bend slightly with respiration and movements of the rib cage.

Development and aging

Costal cartilage develops from mesenchymal tissue during embryogenesis and undergoes endochondral ossification with aging, leading to calcification in many individuals. Calcification and reduced elasticity become more common with advancing age, contributing to stiffness of the thoracic cage.

Function

The rib cartilage provides a semi-rigid yet flexible link between the ribs and the sternum. This elasticity allows the thoracic cage to expand and recoil during breathing, helping to ventilate the lungs while maintaining protection for thoracic organs.

Clinical relevance

Costal cartilage injuries include costochondritis, an inflammation of the costal joints, and Tietze syndrome, which involves costochondral swelling. Fractures or dislocations of costal cartilage can occur with trauma and may complicate imaging and evaluation. Cartilage grafts, including costal cartilage, are used in reconstructive surgery due to their durability and compatibility.