1*54 



HUMAN ANATOMY. 



Portion of injected lung, showing relation of blood- 

 vessels to bronchi; pulmonary- arteries (blue) accompany- 

 ing bronchi (white) ; pulmonary veins (red) at periphery 

 of lobule. X 2 



near the bottom. They arise from the capillaries in the walls of the air-chambers, 

 running first on the outside of the lung-units, unite with others, and ramify in the 

 connrctivr tiuc about the lobules, so that, first in the lung-units and then in the 

 lobules, the circulation is from the centre towards the periphery. As they ascend to 

 tin- hilum they unite with others and form 



trunks that accompany the bronchi, lying FIG. 1 578. 



in the main lower and to the inner side 

 of the latter. Corrosion preparations 

 v. 1578) show very clearly that the 

 MIL ill arteries travel in close company 

 with the bronchi, while the veins course 

 by themselves. 



The bronchial arteries carry the 

 blood for the nutrition of the lungs, es- 

 pecially that of the air-tubes, the lymph- 

 nodes, the walls of the blood-vessels, 

 and the areolar tissue about them ; hence 

 they follow the course of the bronchi. 

 Tht-y are in communication with the 

 interlobular system of the pulmonary 

 arteries. 



The bronchial veins are very irreg- 

 ular. Both anterior and posterior are 

 described. The former carry the blood 

 back from the bronchi and the tissues 

 about them, becoming perceptible at the 



bronchi of the third order (i.e., the branches of the first branches) and running 

 to the hilum anterior to the bronchi, two with each. The posterior bronchial veins 

 appear at the back of the hilum and, without any close connection with the bronchi, 

 anastomose with other veins at the back of the roots of the lungs. 



Anastomoses between the 

 Pulmonary and the Bron- 

 chial Systems. Not only do 

 the capillaries at some places 

 drain into either system of 

 veins, but important com- 

 munications occur between 

 both the arteries and the 

 veins. (a) The bronchial 

 arteries as they enter the 

 lungs give off occasional 

 branches which, running for 

 some distance beneath the 

 pleura, suddenly plunge into 

 the lung to anastomose with 

 an interlobular artery. Such 

 a branch may arise from an 

 cesophageal artery. There 

 are also deep connections 

 between the arteries of the 

 two systems on or near the 

 secondary bronchi and their 

 branches. (b) The com- 

 munications between the two 

 systems of veins are very 



FIG. 



Stction of inject,-,! In,,,- 



Pulmonary v.-in 

 I.Mnph-vesKl 



Mnng, -I,. .!,; Km, ,!,. ...,,, mpanving peripheral 

 branch i.l [>ulm,. ... n\ \, m. < 60, (MuSr.] 



nionarv vi-ins ; and, 



free communication with 



i i iv_i IC.T tduitia ijy inc ijui- 



the bronchial veins about the larger bronchi have 

 of the pulmonary system. According to Zucker- 



