THORACIC CAVITY 



12 5 



Thyreoid cartilage 



Crico-thyreoid 

 ligament 



Cricoid cartilage 



Part of trachea 

 :overed by isthmus 

 of thyreoid gland 



Common carotid 

 artery 



Left subclavian 

 artery 



deficient posteriorly, and, in consequence, the tube is 

 flattened behind (Fig. 57). It enters the thorax at the upper 

 aperture, posterior to the upper border of the manubrium, 

 and it terminates, at the level of the lower border of the 

 manubrium and 

 the upper border 

 of the fifth 

 thoracic vertebra, 

 by dividing into 

 a right and a left 

 bronchus. It lies, 

 therefore, in the 

 superior medias- 

 tinum, and its 

 median axis is in 

 the median plane, 

 except at the 

 lower end, where 

 it deviates slightly 

 to the right. 



Relations. 

 Posteriorly, it is 

 in contact with 

 the oesophagus, 

 which separates it 

 from the verte- 

 bral column; and 

 in the angle 

 between its left 

 border and the 

 anterior surface of 

 the oesophagus is 

 the left recurrent 

 nerve (Fig. 57). 



Anteriorly, it 

 is in relation, 

 below, with the 

 arch of the aorta, the deep part of the cardiac plexus inter- 

 vening ; and, at a higher level, with the innominate and left 

 common carotid arteries, the left innominate vein and the 

 inferior thyreoid veins. More superficially lie the remains of 

 the thymus, and still more superficially the manubrium sterni 



Aortic arch 



Left bronchus 

 Left pulmonary 

 artery 



First ventral 

 branch of 

 bronchus 



right bronchus 

 Hyparterial branch of 

 j right bronchus 

 Right pulmonary artery 



FIG. 63. The Trachea and Bronchi. The dotted 

 line gives the outline of the thyreoid gland. 



