ENDOCRINE GLANDS 



ship of the different organs or, again, as advised by Marf an 

 perform the autopsy in this region by following the opera- 

 tive technique without opening the thoracic cage. The 

 capsule of the thymus being incised, pressure is exerted on 

 the lateral sides of the thorax and this will cause the 

 thymus to rise above the manubrium. It then becomes 

 easy to determine if it is exerting any pressure on the 

 trachea. The question has come up as to how such a soft 

 organ as the thymus could cause any effect on such a 

 resistant organ as the trachea. This is due to the fact 

 that the gland acts less by its weight than by its volume 

 and this varies according to the circulatory conditions. 

 The trachea can also be compressed indirectly by the inter- 

 mediary of the large vessels at the base of the heart. In 

 an observation of Barbier the right trachio cephalic 

 arterial trunk deviated by the thymus had compressed 

 and formed a groove in the trachea, which it com- 

 presses directly. 



The large veins at the base of the neck can also be more 

 and more flattened out by a hypertrophic thymus. Al- 

 though this compression is hard to determine at autopsy it 

 is very probable and such a theory alone could explain the 

 cyanosis increased by extension of the head. 



The compression of certain nerves (vagus, recurrent 

 laryngeal, thymic nerve, etc.) is probable. Cruchet even 

 believes that this nerve compression is more liable to occur 

 than that of the trachea, but there is no definite fact to 

 prove this. 



The mechanical theory of compression is sufficient to" 

 explain the symptoms of hypertrophy of the thymus as it 

 usually occurs, which is characterized by continuous 

 respiratory disturbances. The intermittent type is due 

 without a doubt to congestion of the hypertrophic thymus, 

 usually fairly well tolerated. 



