Joints of the Thorax. 175 



The anterior extremities of the seven (sometimes eight) upper costal cartilages are 

 attached directly to the incisurae costales of the sternum and so form the articulationes 

 sternocostales (articulations of the cartilages of the ribs with the sternum); the 



cartilage of the first rib fuses usually directly with the sternum, while for the cartilages 

 of the second to the seventh rib there are usually present slit-shaped joint cavities and 

 capsulae articular es. A lig amentum sternocostale inter -articular e (0. T. interarticular 

 chondrosternal ligament), which extends from the medial end of the second costal cartilage 

 to the cartilaginous (or bony) junction of the manubrium with the corpus sterni, there 

 constantly divides this joint into two separate joint cavities. In the other joints there 

 are often similar fibrous strands, which, however, lead usually only to incomplete division 

 of the joint cavities. The joint capsules are strengthened on the anterior surface by 

 strong, on the posterior by weak, ligamenta sternocostalia radiata (0. T. anterior and 

 posterior chondrosternal ligaments), which extend from the ends of the costal cartilages, 

 diverging to the sternum; the anterior of these interweave with those of the other side 

 to form a tough layer. This layer, ensheathing the sternum in front and behind, is 

 called the membrana sterni. 



The eighth and ninth rib are attached usually (see p. 78) each with the anterior 

 end of its cartilage to the cartilage of the next rib above. In these places as well as 

 sometimes at other places on the fifth to the ninth costal cartilage, where contact 

 between the cartilages or cartilaginous processes takes place, small joint slits and joint 

 capsules are present, the articulationes inter chondr ales. 



The anterior extremity of the tenth costal cartilage is united by a loose liga- 

 mentous band with the ninth; no such connection of the eleventh with the twelfth 

 rib exists. 



From the lowermost end of the corpus sterni and from the anterior surface of 

 the sixth and seventh costal cartilage strand-like bands go off obliquely medianward to 

 the anterior surface of the processus xiphoideus, the ligamenta costoxipholdea (0. T. 

 chondroxiphoid ligaments). They are connected with the anterior leaf of the vagina 

 musculi recti abdominis. 



