The intraarticular sternocostal ligament (Interarticular Sternocostal Ligament ) ligament is found constantly only between the second costal cartilages and the sternum.
The cartilage of the second rib is connected with the sternum by means of an interarticular ligament, attached by one end to the cartilage of the rib, and by the other to the fibrocartilage which unites the manubrium and body of the sternum. This articulation is provided with two synovial membranes.
Occasionally the cartilage of the third rib is connected with the first and second pieces of the body of the sternum by an interarticular ligament.
Still more rarely, similar ligaments are found in the other four joints of the series. In the lower two the ligament sometimes completely obliterates the cavity, so as to convert the articulation into an amphiarthrosis.