468 GENERAL REMARKS UPON THE CHEST. 



and situated on the posterior surface of the articula- 

 tion. 



The superior and inferior costo-sternal ligaments are simply 

 narrow fasciculi of fibres, connecting the upper and lower 

 margins of the sternal end of the costal cartilages with the 

 sides of the sternum. 



The cartilage of the first rib, it seems, has no synovial 

 membrane, and is continuous with that of the sternum. 

 The cartilage of the second rib, at its junction with the 

 sternum, like the heads of the ribs, is divided by a liga- 

 mentous partition, forming two cavities and two synovial 

 membranes. The sixth, seventh, and eighth, and occasion- 

 ally the fifth and ninth, have articulations with each other 

 lined by a synovial membrane. External and internal liga- 

 mentous fibres pass from one to the other. Ligamentous 

 fibres are seen passing from the cartilage of the seventh 

 rib near the sternum, and spreading themselves over the 

 anterior surface of the xiphoid ligament, and are named 

 costo-xiphoid ligaments. The motion of the ribs at the 

 sternum is very limited. 



GENERAL REMARKS UPON THE CHEST. 



The Chest thus composed of the sternum, ribs, costal car- 

 tilages, and dorsal vertebras, all bound together by the 

 ligaments, presents a large and very important cavity for 

 containing the lungs, the organs of respiration, and the 

 heart, the chief agent of circulation. 



This cavity, which in the skeleton is continuous with the 

 abdominal, in the fresh subject is separated from the latter 

 by the diaphragm. When the arms are detached from the 

 trunk it presents the form of a truncated cone, having 

 the apex above and the base below, flattened before and 

 behind, and convex at the sides. This form of the chest, 

 however, may be materially altered by tight lacing, and 

 by disease. The anterior wall is, as already stated, shorter 

 and more oblique than the posterior, which is vertical. Its 

 surface is rendered very irregular by grooves, processes, and 

 angles. The intercostal spaces are wider in front than 



