316 CLINICAL APPLIED ANATOMY. 



More rarely the primary lesion lies further outwards, corre- 

 sponding to the first and second interspaces below the outer 

 third of the clavicle. It is exceptional for a lower lobe to be 

 directly invaded across the interlobar fissure the pleura appears 

 to have sufficient power of resistance to prevent this. Secondary 

 deposits in the other lobes are the result of aspiration from the 

 primary focus. 



The lower lobe is usually invaded before the mischief has 

 extended very far in the upper lobe, the middle lobe being 

 passed over. The first focus in the lower lobe is an inch or 

 an inch and a half below the apex and the same distance from 

 the posterior border. Here, again, extension takes place back- 

 wards towards the posterior border of the lung, corresponding to 

 an area on the chest wall midway between the fifth dorsal spine 

 and the vertebral border of the scapula, and also laterally along 

 the line of the great fissure. This line is sufficiently well indi- 

 cated by placing the hand upon the spine of the opposite scapula 

 and raising the elbow above the level of the shoulder. The 

 vertebral border of the scapula then corresponds fairly with the 

 oblique fissure. 



Infections of the opposite lung usually occupy positions 

 similar to those of the lesions in the lung first involved, but 

 occasionally the opposite upper lobe shows a deposit correspond- 

 ing to the upper part of the axilla, just above the interlobar 

 septum, hence the axilla as well as the apices should always be 

 carefully examined. In children and women with thinly covered 

 chests, bronchial breathing may often be heard over the manu- 

 brium sterni and upper part of the sternum, and also in the 

 interscapular region. These points correspond to the termina- 

 tion of the trachea and the commencement of the main bronchi. 

 At its point of bifurcation the trachea lies under the right edge 

 of the sternum. The bifurcation corresponds to the level of the 

 sterno-manubrial joint in front, and the tip of the fourth dorsal 

 spine behind, these being the surface levels of the disc between 

 the fourth and fifth dorsal vertebra. It is sometimes stated that 

 the bifurcation is on the same level as the root of the scapular 



