COSTO-STERNAL AND INTERCOSTAL. 



201 



may be demonstrated by removing a thin section from the anterior surface of the 

 sternum and cartilages, as seen in fig. 126. After middle life, the articular 

 surfaces lose their polish, become roughened, and the synovial membranes appear 

 to be wanting. In old age, the articulations do not exist, the cartilages of most 

 of the ribs becoming firmly united to the sternum. The cartilage of the seventh 



Fig. 126. Costo-sternal, Costo-xiphoid, and Intercostal Articulations. Anterior View. 



ITie tynm'ufl cavitie* fxpoted 

 by a, vertical itctwn aftk* Sternum k 



\ Single Synmx'al 

 Membrane 



rib, and occasionally also that of the sixth, is connected to the anterior surface of 

 the ensiform appendix, by a band of ligamentous fibres, which varies in length 

 and breadth in different subjects. It is called the costo-xiphoid ligament. 



Actions. The movements which are permitted in the costo-sternal articulations 

 are limited to elevation and depression ; and these only to a slight extent 





