TUBEECULOSIS OF MEDIASTINAL GLANDS. 339 



vertebrae into the thorax considerably narrows the antero- 

 posterior diameter, especially above, where the trachea and 

 bronchi lie. Hence a growth in the superior mediastinum 

 is in a very favourable position to produce pressure on the air 

 passages, and, moreover, it is in this locality that the most 

 important groups of lymphatic glands, the residue of the thymus 

 and aberrant thyroids are most likely to be found. 



Dyspnoea may also be the result of pericardial and pleural 

 effusions. The relations of the serous sacs to the mediastinum 

 and its contained glands, the fact that the efferent lymphatics 

 and veins of the sacs pass to the mediastinum, and the continuity 

 of the connective tissue basis of the sacs with the mediastinal 

 tissue, sufficiently account for the passive effusions and inflam- 

 matory affections which are found associated with growth in the 

 thorax. 



TUBERCULOSIS OF MEDIASTINAL GLANDS. 



In childhood the peritracheo-bronchial group of lymphatic 

 glands often becomes tuberculous. The cardiac group of glands 

 may also become involved. The glands first mentioned receive 

 the lymphatics of the lung and visceral pleura, of the heart and 

 pericardium, and in part of the thymus and oesophagus. The 

 serial prolongation of the glands into the lungs explains the 

 frequent occurrence of islets of caseation near the roots in 

 children. The anatomical relations of the glands have been 

 described already. They are in a favourable position to produce 

 vagus irritation and so give rise to a dry cough. Occasionally 

 the recurrent laryngeal nerves are implicated, and laryngeal 

 paralysis observed. The glands may interfere with the air entry 

 into a whole lung or one of its lobes, and if very large may 

 produce dulness, with increased conduction of the voice and 

 breath sounds, in the interscapular or upper sternal regions. A 

 venous hum heard over the manubrium sterni when the head is 

 fully retracted is supposed to indicate pressure on one of the 

 venous trunks of the mediastinum. Traction diverticula of the 



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