34 



THE RESPIRATORY SYSTEM 



aorta (Fig. 113), and, therefore, may be subjected to pressure 

 by aneurismal dilatations. It also lies behind the remains of 

 the thymus gland, and may be compressed by tumours which 

 have their origin in that structure. 



Epiglottis 

 Hyoid bone 



Thyreo-hyoid 

 membrane 



Thyreoid cartilage 

 (laryngeal prominence) 



Crico-thyreoid ligament 

 Cricoid cartilage 



Right bronchus 

 Eparterial bronchus - 



FIG. 121. The Larynx, Trachea and Bronchi. 



As the oesophagus is interposed between the trachea and the 

 vertebral column, tumours which cause respiratory embarrass- 

 ment by exercising pressure on the trachea may also give rise 

 to difficulty in swallowing (Fig. 113). 



The two Bronchi, nto which the trachea bifurcates, differ 



