Costal cartilage is a type of cartilage that connects the ribs to the sternum (breastbone). It is made of flexible tissue, allowing the rib cage to expand and contract during breathing. This flexibility is essential for protecting vital organs in the chest while enabling the lungs to fill with air. In addition to its role in the rib cage, costal cartilage contributes to the overall structure and support of the thoracic skeleton. It helps maintain the shape of the chest and provides a smooth surface for the ribs to move against, facilitating efficient respiratory function.