THE LUNGS. 1855 



kandl,' the pulmonary veins anastomose freely with those of the organs of the pos- 

 terior mediastinum, and even of the portal system. 



The lymphatics of the lung are very numerous. The deeper ones probably 

 begin as lymph-spaces within the interalveolar septa, distal to the terminal bronchi, 

 distinct lymphatics being found only along the arteries and veins. . These commu- 

 nicate with the subpleural lymphatic plexus. Surrounding the walls of the terminal 

 bronchi Miller found usually three lymph-vessels. The latter increase in size and 

 number as the calibre of the air-tubes enlarges. On reaching the bronchi the lym- 

 phatics form plexuses along them which ultimately open into the lymphatic nodes, 

 which are numerous in the hilum and in the roots of the lungs. According to Miller, 

 where cartilage-rings are present a double net-work exists, one on each side of the 

 cartilage, the inner lying within the submucosa. The lymph-nodes of the lungs are 

 deeply pigmented, owing to the colored particles of foreign substances inspired. 



Nerves. — The nerves of the lungs, from the pneumogastrics and sympathetics, 

 form the very rich anterior and posterior pulmonary plexuses about the roots, whence 

 they enter the lungs, running along the branches of the bronchial arteries and the 

 bronchi to their ultimate distribution in the septa between the alveoli (Retzius, Berk- 

 ley). The nerves are destined chiefly for the walls of the blood-vessels and of the air- 

 tubes. Berkley describes interepithelial end-arborizations within the smaller bronchi. 



THE RELATIONS OF THE' LUNGS TO THE THORACIC WALLS. 



The relations of the median and diaphragmatic surfaces of the lungs have been 

 given (page 1844). The apex rises vertically about 3 cm. above the level of the upper 

 border of the first costal cartilage and about i cm. above the level of the clavicle. 

 These distances are to be reckoned on a vertical plane, not on the slanting surface of 

 the root of the neck. They vary extremely, depending, as they do, on the formation 

 of the body. Thus a sunken chest, which means a very oblique first rib, would have 

 more lung above the cartilage than a full chest with a more nearly horizontal first rib. 

 In extreme cases the lung may rise as much as 5 cm., or as little as i cm., above the 

 first cartilage. The plane of the inlet of the chest is made by the oblique first ribs. 

 The fibrous parts enclosing it are dome-like, the roof of the cavity, to which the lung 

 is closely applied, swelling upward perhaps i cm. above this oblique plane ; the 

 top of the lung, however, is never above the level of the neck of the first rib. It 

 was formerly taught that the right lung rises higher than the left. As a rule, there is 

 no appreciable difference between the two sides. The most that can be said for the 

 Did view is that, if there be some trifling difference, it is probably rather more often 

 in favor of the right. The anterior borders of the lungs descend obliquely behind 

 the sterno-clavicular joints, and curve forward so as to nearly, or quite, meet in the 

 median line on the level of the junction of the manubrium and body of the sternum. 

 Below this the right lung extends a little across the median line and the left recedes 

 slightly from it. The right border leaves the sternum at the sixth right costal carti- 

 lage, to which it has gradually curved, runs along that same cartilage, or a little above 

 it, to its junction with the sixth rib, then crosses the ribs, passing the eighth at about 

 the axillary line, and reaches the spine at the eleventh rib or a little higher, the 

 guide being the spine of the tenth thoracic vertebra. The lowest part of the lung is 

 on the side at the axillary line or behind it, but the line thence along the back, 

 although rising a little, is very nearly horizontal. The course of the border of the left 

 lung is essentially the same, except that, leaving the sternum at the fourth cartilage, 

 or at the space above it, the border describes a curxe with an outward convexity, 

 exposing a large piece of the pericardium, and turns forward to end as the lingula 

 opposite the sixth cartilage, some distance to the left of the sternum. As this point 

 depends on the development of the lingula, it cannot be stated accurately. It may 

 be said in general to be 3 or 4 cm. to the left of the median line. The greatest depth 

 of this curve is in the fourth intercostal space, about 5 cm. from the median line. The 

 course of the inferior border along the side and back is practicallv that of the right 

 one, although, perhaps, the left lung may descend a trifle lower at the side. At the 

 back the lower borders are very symmetrical. 



1 Sitzungsberichle cl. Wiener Akad., Bd. Ixxxiv., 1881. 



