Prolonging the ribs into a forward motion, the costal cartilage allows for the thorax to maintain elasticity in the walls. There are twelve costal cartilage sections. Each has two cartilages, extremities, and borders. Seven pairs of the costal cartilage are connected to the sternum. Two of the costal cartilage sections are pointed, ending in the walls of the abdomen. Three pairs of costal cartilage are articulated with the preceding ribs. In the surfaces, anterior surfaces are convex. The posterior surfaces are concave. The borders are superior and inferior in nature. The superior section is concave, while the inferior is convex. In the extremities, the osseous tissue and the lateral end of the cartilage are continuous. The eleventh and twelfth costal cartilage sections are pointed and are free of attachments. Once costal cartilage reaches old age, the cartilage becomes prone to superficial ossification. At the inferior borders, heel-like projections may be created in areas of convexity along the sixth, seventh, eighth, and ninth pieces of costal cartilage.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Costal cartilage