192 The Lungs 



taking the metallic note of the distended and elevated stomach for 

 that of a pulmonary cavity or of a pneumo- 

 thorax. 



IX The lower border of the lung descends 



about an inch during inspiration, but in 

 emphysema, when the air-vesicles are per- 

 X manently dilated and inelastic, there is no 

 movement in the costo-phrenic crevice. 



The thick, posterior border lies in the 

 costo-vertebral groove ; the sharp, anterior 

 border overlaps the pericardium. The inner 

 surface of the lung is concave, the root enter- 

 ing it nearer to the back than the front. The 

 thickness of the posterior border is well shown 

 on p. 1 86. 



The left lung (20 oz.) has two lobes ; it is 

 narrower than the right, so as to leave a 

 hollow for the heart. The fissure between 

 the lobes extends from the spine of the sca- 

 pula (that is from the third rib behind) to the 

 base of the lung in front. The upper is the 

 anterior lobe. 



The right lung (22 oz.) is the larger, 

 because it does not have to make room for 

 the heart ; but it is shorter on account of the presence >of the liver 

 beneath it ; it has three lobes, the third being sliced off the bottom of 

 the upper lobe by a fissure running upwards and forwards. The middle 

 lobe lies under cover of the fourth, fifth, and 

 sixth ribs, at the side of the chest, and in front 

 it reaches to the diaphragm. 



It is important to remember that the fissure 

 between the upper and lower lobes extends from 

 the third rib behind (spine of scapula) to the 

 base of the lung in front. Thus, in pneumonia 

 of the lower lobe the dulness is found ending 

 abruptly at that oblique line, together with 

 the bronchial breathing and increased vocal 

 vibration ; above that line all is healthy. And 

 conversely, in phthisis, which has a prefer- 

 ence for the upper lobe, the dull percussion 

 sound posteriorly is above the spine of the 



Pneumonia of lower lobe , . , ., 



scapula only, whilst in front it extends down to 

 the diaphragm. The lower lobe is almost alto- 

 gether behind the upper lobe. 

 The lower dorsal vertebra: advance into the interior of the chest, 

 the ribs all the while receding, so that if a line be drawn across the 



Right costo-phrenic crevice 

 seen from behind. A stab 

 of the liver through the gth 

 space would traverse four 

 layers of pleura and two of 

 peritoneum ; if through the 

 nth space the lung would 

 escape injury. 



(2) of right lung ; dulnt 

 below spine of scapula, 

 front resonant. 



