60 THORAX 



postero-lateral aspect of the stem bronchus, between the ventral 

 and dorsal hyparterial branches, and note that its branches 

 correspond with the branches of the bronchus and run chiefly 

 along their posterior aspects. 



On the left side follow, first, the upper pulmonary vein, and 

 note that its tributaries are derived only from the upper lobe of 

 the left lung. Then follow the lower vein, which receives blood 

 from the lower lobe. After the veins are displayed clean the 

 hyparterial part of the stem bronchus and its ventral and dorsal 

 branches, cleaning the dorsal branches from their medial sides. 

 Note that the first ventral branch is relatively very large and that 

 it is distributed entirely to the upper lobe, whilst all the other 

 branches, ventral and dorsal, are distributed to the lower lobe. 

 Finally, follow the pulmonary artery along the postero-lateral 

 face of the stem bronchus, and note that it gives off branches 

 which correspond, in number and position, with the branches 

 of the bronchus and that they run along the posterior aspects of 

 the bronchi which they accompany (Fig. 25). 



Bronchi. There are two primary bronchi, one for each 

 lung. They spring from the termination of the trachea and 

 each passes downwards and laterally to the hilum of the lung 

 to which it belongs; then, having entered the lung through 

 the hilum, it descends, in the substance of the lung, to the 

 base. The dissector who has followed the preceding instructions 

 will have noted that as the main bronchial stem traverses the 

 lung substance it lies nearer the medial than the lateral surface 

 of the lung and nearer the posterior than the anterior border. 

 And he should also have noted that the apex of the lung is 

 supplied by branches which ascend to it, whilst the other 

 parts are supplied by branches of the bronchus which run 

 mainly forwards or backwards, many of the branches having 

 an inclination downwards. 



The relations of the extra-pulmonary portions of the bronchi, 

 which lie between the trachea and the lungs, cannot be 

 completely studied at present. The intra-pulmonary relations 

 are simple. On the right side the eparterial branch enters the 

 upper lobe of the right lung accompanied by a branch of the 

 superior right pulmonary vein and a branch of the right 

 pulmonary artery. It breaks up in the substance of the upper 

 lobe into numerous ramifications, all of which are accompanied 

 by a corresponding pulmonary vein and artery. Below the 

 eparterial branch the stem bronchus descends into the lower 

 lobe, and as it descends it gives off a series of ventral and 

 dorsal branches which arise alternately. Each branch is 

 accompanied by a tributary of the pulmonary vein and a 

 branch of the pulmonary artery. The first ventral branch is 



