THE TRACHEA. 



We have made measurements on two casts from frozen sections of the adult, and one from 

 a section of a child thought to be of about three years, and have calculated the angles between the 

 prolongation of the axis of the terminal part of the windpipe and that of each bronchus. An 

 attempt was also made to measure, the angles from a skiagraph made by Blake l after injecting 

 fusible metal into the trachea of a hardened body. Two observations on adults by Kobler and 

 v. Hovorka 2 are included for comparison. 



It seems that the subtracheal angle, that of divergence of the bronchi, is about 70. We have 

 found it precisely that in another specimen. Kobler and v. Hovorka measured the lateral 

 angles in the hardened bodies of sixteen new-born infants. The average was right 25.6, left 

 48.9. The variations ranged on the right from 10 to 35 and on the left from 30 to 65. We 

 found their average angle of divergence 74.5. This shows that, contrary to the general im- 

 pression, the bronchi are not more nearly vertical in the infant than subsequently. Aeby gives 

 the angles of divergence of two new-born children as 33 and 61 ; Mettenheimer 3 as 50 and 63. 



Vessels. The pulmonary artery at its bifurcation is anterior to the bronchi 

 and at a lower plane. Each branch of the artery rises over the bronchus and comes 

 to lie more or less external to it. This apparent crossing of the bronchus by the 

 artery occurs on the right just after the origin of the first secondary bronchus. The 

 usual teaching, following Aeby, that the artery actually arches over the extrapul- 



FIG. 1563. 



Sternum 



Pulmonary semilunar valve 



Left lung- 



Aorta 



Superior vena cava 



Parietal pleura 

 Visceral pleura 



Left pulmonary 

 veins 



Left bronchus 



Reflection of visceral 

 onto mediastinal pleura 



III rib 

 Right bronchus 



Right lung 



Thoracic aorta 



Body of vertebra (Esophagus 

 Right pulmonary artery 



Spine of scapula 

 Superior fissure 



Transverse section of thorax at level of fifth thoracic vertebra. 



monary bronchus and lies behind it, is incorrect. The artery divides before enter- 

 ing the lung, one branch entering through the upper and the other through the 

 lower part of the hilum. 



The pulmonary veins are usually two on each side. The superior lie in front of 

 and below the artery. The inferior are the lowest of the large vessels of the lung- 

 root, passing from behind under the bronchus into the heart. 



The bronchial arteries follow the bronchi along their posterior surfaces. The 

 bronchial veins are both anterior and posterior. On the right side both open into 

 the larger azygos vein. The left posterior ones often receive the anterior and open 

 into the superior hemiazygos. There may be various anastomoses with mediastinal, 

 pericardial, and tracheal veins. 



The lymphatics run for the most part behind the bronchi. The lymph-nodes 

 are for the most part on the posterior and inferior aspects of the tubes, the group 

 under the bifurcation joining others at the sides. Some nodes occur on the front. 



The nerves from the sympathetic and vagus form plexuses both before and 

 behind the bronchi. 



1 American Journal of the Medical Sciences, 1899. 

 * Sitzbericht. Acad., Vienna, 1893. 

 3 Morpholog. Arbeit. Schwalbe, 1894. 



