kostalcartilage

Costal cartilage, or kostal cartilage in some texts, refers to the hyaline cartilage bars that connect the anterior ends of the ribs to the sternum or to the cartilage of the rib above. Together they form the costal arches of the thoracic cage and contribute to the rib cage’s flexibility during breathing.

Anatomy and connections: Most ribs have costal cartilage that directly articulates with the sternum (ribs 1–7). Ribs 8–10 connect indirectly to the sternum via the cartilage of the rib above. Ribs 11 and 12 are floating; their anterior cartilages do not reach the sternum. The cartilage is avascular and relies on diffusion for nourishment, and is surrounded by a perichondrium. The tissue is hyaline cartilage.

Development and aging: Costal cartilage originates from mesenchymal tissue in the thoracic wall during embryonic development. With age, costal cartilage can calcify and partially ossify, reducing flexibility in some older individuals. Calcification may be visible on imaging without indicating disease in many adults.

Function: The costal cartilages lengthen the anterior rib cage and allow elastic deformation of the thoracic wall during respiration, enabling expansion and recoil while protecting the lungs and heart.

Clinical significance and variation: Inflammation at the costochondral junction, known as costochondritis, or the related Tietze syndrome, can cause chest wall pain. Traumatic injury or fractures can involve the costochondral joints. Costal cartilage grafts are used in reconstructive procedures and can be harvested for various cosmetic and reconstructive applications.