THE LUNGS 353 



Tropical abscess of the liver causes adhesions to form between 

 the liver and the diaphragm, and it may burst through the 

 diaphragm into the right pleural sac, giving rise to an 

 empyaema. If the diaphragmatic pleura is adherent, to the 

 base of the lung, the abscess may rupture into the lung and 

 be discharged by coughing. It should be remembered that 

 the cough reflex is not brought about until the pus comes into 

 contact with the trachea or, perhaps, with one of the larger 

 bronchi. As a result, in these cases and in bronchiectasis and 

 large phthisical cavities, once the cough reflex is started, it is 

 continued until all the movable pus is evacuated. The 

 patient then enjoys a quiescent period until a fresh accumula- 

 tion reaches the larger air-passages and so induces another 

 outbreak. 



The Base of the Left Lung overlies the left lobe of the liver, 

 the stomach and the upper half of the spleen (p. 404). 



The mediastinal surface of the right lung is in relation, 

 below and in front of the hilum, to the pericardium covering 

 the right atrium. Above the hilum, it is in direct contact with 

 the trachea, and this relationship helps to explain why bronchial 

 breathing may be heard on ausculting a perfectly healthy right 

 apex (p. 341). Above the hilum of the left lung, the trachea is 

 separated from the mediastinal surface by the left subclavian 

 artery, but the oesophagus, which projects slightly to the left 

 side of the median plane, and the thoracic duct are often in 

 direct apposition. On this account, cesophageal sounds may 

 be audible at the left apex. 



The Lymph Vessels of the lung join the broncho-pulmonary 

 lymph glands, which are situated in the neighbourhood of the 

 hilum. Some of the efferents from these glands pass directly 

 to the thoracic duct, but others join the glands around the 

 bifurcation of the trachea. From the latter group, efferents 

 pass upwards to the para-tracheal glands, which communicate 

 freely with the inferior group of the deep cervical glands. 

 This indirect connexion between the lymph vessels of the 

 lung and the cervical glands may offer a channel for the 

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