16 CLINICAL APPLIED ANATOMY. 



squamous epithelium. Moreover, neither food nor sputum tarry 

 long in these situations. When tuberculosis attacks the tongue 

 the ulcers are usually on the margins, near the tip, positions 

 presumably liable to slight injury. 



The stomach and upper part of the small intestine usually 

 escape, the former on account of its motor activity and acid 

 contents and the latter because of the scantiness of its lymphoid 

 tissue and the rapid passage of its contents. The discharge of 

 the bile and pancreatic juice into the second part of the duodenum 

 also conduces to the immunity of the upper part of the small 

 bowel. There are certain positions in which the digestive tract 

 may become locally involved by extensions of the tuberculous 

 process from lymphatic glands. The upper part of the pharynx 

 may be infected from retro-pharyngeal glands which drain the 

 nasal fossae, and the oesophagus may be invaded by tuberculous 

 glands of the mediastinum. 



The respiratory Iract is likewise exposed to direct infection. 

 The nose is particularly well guarded against invasion. The 

 vestibule is lined by thick skin as far back as the limen nasi, and, 

 moreover, is armed with thick recurved vibrissse. The 

 Schneiderian membrane is thick, erectile, endowed with very 

 high reflex excitability, and freely provided with a rnucoid 

 secretion inimical to bacterial growth. The ciliated epithelium 

 of the respiratory portion of the nose is an additional protection. 

 Notwithstanding all this, tuberculosis does at times invade the 

 nasal cavities. The infection may be introduced on the finger, 

 and slight injury at the same time inflicted ; tuberculous sputum 

 may lodge in the nasal cavity as the result of imperfect cough, or 

 invasion may occur by continuity of tissue. 



The complicated structure of the larynx, its exposure to cough 

 pressure, and the absence of ciliated epithelium on its cords, 

 render it very liable to infection by tuberculous sputum during 

 cough. By virtue of its position it may also become primarily 

 infected, but this is exceptional. 



In pulmonary phthisis it is said that the larynx is often 

 involved on the same side as the diseased lung. The accuracy of 



