LUNGS . 135 



and the part covering the lungs the visceral pleura. The 

 latter is very thin and adherent to the lung, and dips into all the 

 fissures. 



The parietal pleura is named according to the part over which 

 it passes. The cervical pleura rises up to the level of the neck 

 of the first rib. Owing to the oblique position of the latter, the 

 pleura is about an inch and a half above the level of the clavicle ; 

 it is strengthened by Sibson's fascia, a strong membrane 

 attached to the seventh cervical vertebra and the inner margin 

 of the first rib. The costal pleura lines the inner surfaces of 



STERNUM 



FIG. 53. THE PLEURA. 



the ribs and the intercostal spaces ; it reaches to the sternum 

 in front and the bodies of the vertebrae behind. The 

 diaphragmatic pleura covers the surface of the diaphragm 

 except for the middle part, occupied by the pericardium, and a 

 narrow strip at the costal attachment. The mediastinal pleura 

 passes back from the sternum to the vertebral column and lines 

 the space (mediastinum) between the lungs. As it passes back 

 it is reflected by the root on to the lung, and becomes the visceral 

 pleura (see Fig. 53). Below the root of the lung the two layers 

 hang down in a deep fold called the ligamentum latum pulmonis. 

 The parietal pleura is bigger than the lungs require at rest, 



