i8 



THORAX 



medial surface, where it is attached to the heart by the 

 pulmonary vessels ; to the corresponding bronchial tube ; and, 

 by a fold of pleura, to the side of the pericardium. 



The dissection which has already been made shows the 

 pleura lining the deep surfaces of the costal arches and the 

 internal intercostal muscles. That part is called the costal 

 pleura, and it is part of the parietal pleura. The student 

 must understand that the term costal pleura is applied only to 

 that part of the parietal pleura which lines the costal part 

 of the thoracic wall ; the part which covers the mediastinum 



Costal part of parietal pleura 



Pleural cavity ^ 

 Visceral pleura 



Costal part of parietal pleura 

 Pleural cavity 

 Visceral pleura 



FIG. 5. Diagrammatic representation of a cross section through 

 the Thorax. 



is called mediastinal pleura, the part which covers the upper 

 surface of the diaphragm is the diaphragmatic pleura, and the 

 part which projects into the root of the neck is spoken of as 

 the apical or cervical pleura. Before the costal pleura can be 

 more fully investigated, and before the remaining parts of 

 the pleurae and the lungs can be examined, further dissection 

 is necessary. 



Dissection. The pleural membrane previously exposed by 

 the removal of the contents of the intercostal spaces must now 

 be carefully separated from the inner surfaces of the ribs by 

 gentle pressure of the fingers. The separation should be carried 

 anteriorly to the junction of the ribs with their cartilages and 

 posteriorly as far as possible. When that has been done, the 



