256 ANATOMY IN A NUTSHELL. 



lungs by the bronchial arteries, for that part which is distributed to the smaller 

 bronchial tubes and alveolae is brought back by the pulmonary veins. The 

 right bronchial vein empties into the vena azygos major just before that vein 

 empties into the superior vena cava. The left bronchial vein empties into the 

 lower left superior intercostal vein or into the vena azygos tertius. Small 

 veins from the bronchial glands, from the trachea, and from the posterior med- 

 iastinum empty into the bronchial veins at the root of the lung. The lymphatics 

 of the lungs are numerous. 



The base of each lung rests upon the Diaphragm and its apex passes through 

 the superior opening of the thorax about an inch above the clavicle. Each 

 lung is pyramidal in form and the right one is divided into an upper lobe, a 

 middle lobe, and a lower lobe, while the left lung is divided into an upper lobe 

 and a lower lobe. The root of each lung is little above the middle at the inner 

 side and except for this attachment the lung lies free in the pleural cavity which 

 it completely fills. The lung is elastic and always on a tension. The blood in 

 passing through the lungs gives off carbon dioxide to the air in the alveolae and 

 receives oxygen. This process which takes place in the lung is a simple physical 

 change and has nothing to do with any secreting or other activity of the epi- 

 thelial cells. 



Nerve Supply. — It is from the anterior and posterior pulmonary plexuses, 

 which are formed from the sympathetic and pneumogastric. Filaments from 

 these plexuses accompany the bronchial tubes upon which they are lost. Small 

 ganglia are formed upon these nerves. 



The right lung (Plates CXXI-CXXII-CXXIII.) weighs twenty-two ounces 

 and the left one twenty. Their capacity is nearly seven and a half pints. The 

 entire respiratory surface is more than eight hundred and seventy square feet. 

 At birth the lungs are a reddish brown and change to a rose pink on inflation. 

 They are grayish white in adult life and brownish in middle life and bluish 

 black in old age. The specific gravity varies from 345 to 746, water being 1000. 

 The serous membrane which covers the lung is the pleura . (Plates CXXY-CXXVL) 

 Each pleura is an inclosed sac and they do not touch each other. Each has a 

 parietal layer called a costal, and a visceral layer called pulmonary. The 

 movements of the lungs in the chest are facilitated by serous secretion in the 

 pleura. The parietal pleura has different names for its various portions. 



1. Tin-: costal pleura is that which lines the ribs, costal cartilages, and 

 intermediate muscles. 



2. The diaphragm \tic pleura is that which is attached to the Diaphragm. 



3. The mediastinal pleura is that which is attached to the adjacent 

 structures in the mediastinum. 



4. The < i;k\ ecal pleura is that which covers the dome of the lung. 

 Blood Supply. — Internal mammary, intercostal, musculo-phrenic, thymic, 



pericardiac, bronchial. The veins correspond to the arteries. The lymphatics 

 are numerous. 



Nerve Supply. — Sympathetic and phrenic. 



The broad ligamenl of the lung is a fold of the visceral layer of the pleura 

 which after covering the root of the lung comes together directly beneath it 



