1120 THE ORGANS OF VOICE AND RESPIRATION. 



oxygenated blood to the left auricle of the heart. The radicles come together in 

 the septa between the infundibula, entirely separate from the small arterial ramifi- 

 cations. Those which are near the surface of the lung have an undivided course 

 for some distance and then either unite with some deeper lying vein or form, with 

 their companions, a wide-meshed superficial plexus. 



The bronchial arteries supply blood for the nutrition of the lung : they are 

 derived from the thoracic aorta, and, accompanying the bronchial tubes, are dis- 

 tributed to the bronchial glands and upon the walls of the larger bronchial tubes 

 and pulmonary vessels. Those supplying the bronchial tubes form a capillary 

 plexus in the muscular coat, from which branches are given off to form a second 

 plexus in the mucous coat. This plexus in the lobular branchioles is continuous 

 with that of the pulmonary artery, and the blood which the bronchial artery brings 

 is thus carried back by the pulmonary vein. Others are distributed in the inter- 

 lobular areolar tissue, and terminate partly in the deep, partly in the superficial, 

 bronchial veins. Lastly, some ramify upon the surface of the lung beneath the 

 pleura, where they form a capillary network. 



The bronchial vein is formed at the root of the lung, receiving superficial and 

 deep veins corresponding to branches of the bronchial artery. It does not, how- 

 ever, receive all the blood supplied by the artery, as some of it passes into the 

 pulmonary vein. It terminates on the right side in the vena azygos major, and 

 on the left side in the superior intercostal or left upper azygos vein. Some author- 

 ities, especially Zuckerkandl, state that, in other parts of the lung than in the 

 lobular branchioles, bronchial veins, even those coming from the larger bronchial 

 tubes, join more or less freely with pulmonary veins. The intercostal arteries give 

 small branches to the surface of the lung, by way of the ligamentum latum pul- 

 monis. (Turner.) 



The lymphatics consist of a superficial and deep set : they terminate at the 

 root of the lung, in the bronchial glands. 



Nerves. The lungs are supplied from the anterior and posterior pulmonary 

 plexuses, formed chiefly by branches from the sympathetic and pneumogastric. 

 The filaments from these plexuses accompany the bronchial tubes, upon which 

 they are lost. Small ganglia are found upon these nerves. 



Surface Form. The apex of the lung is situated in the neck, behind the interval between 

 the two heads of origin of the Sterno-mastoid. The height to which it rises above the clavicle 

 varies very considerably, but is generally about one inch. It may, however, extend as much as 

 an inch and a half or an inch and three-quarters, or, on the other hand, it may scarcely project 

 above the level of this bone. In order to mark out the anterior margin of the lung, a line is 

 to be drawn from the apex-point, one inch above the level of the clavicle, and rather nearer the 

 posterior than the anterior border of the Sterno-mastoid muscle, downward and inward across 

 the sterno-clavicular articulation and first piece of the sternum until it meets, or .almost meets, 

 its fellow of the other side opposite the articulation of the manubrium and gladiolus. From this 

 point the two lines are to be drawn downward, one on either side of the mesial line and close to 

 it, as far as the level of the articulation of the fourth costal cartilages to the sternum. From 

 here the two" lines diverge ; the left is to be drawn at first passing outward with a slight inclina- 

 tion downward, and then taking a bend downward with a slight inclination outward to the apex 

 of the heart^ and thence to the sixth costo-chondral articulation. The direction of the anterior 

 border of this part of the left lung is denoted with sufficient accuracy by a curved line with its 

 convexity directed upward and outward from the articulation of the fourth right costal cartilage 

 of the sternum to the fifth intercostal space, an inch and a half below and three-quarters of an 

 inch internal to the left nipple. The continuation of the anterior border of the right lung is 

 marked by a prolongation of its line from the level of the fourth costal cartilages vertically 

 downward as far as the sixth, when it slopes off along the line of the sixth costal cartilage to its 

 articulation with the rib. 



The lower border of the lung is marked out by a slightly curved line with its convexity down- 

 ward from the articulation of the sixth costal cartilage to its rib to the spinous process of the 

 tenth dorsal vertebra. If vertical lines are drawn downward from the nipple, the mid-axillary 

 line, and the apex of the scapula, while the arms are raised from the sides, they should intersect 

 this convex line, the first at the sixth, the second at the eighth, and the third at the tenth rib. 

 It will thus be seen that the pleura (seepage 11 14) extends farther down than the lung, so that 

 it may be wounded, and a wound pass through its cavity into the Diaphragm, and even injure 

 the abdominal viscera, without the lung being involved. 



The posterior border of the lung is indicated by a line drawn from the level of the spinous 



