54 



Topography 



390. Topography of the Thoracic Viscera. 



Owing to the oblique position of the heart, towards the left side, the anterior 

 mediastinum is not parallel with the sternum, but directed obliquely from above 

 downwards and to the left of the median line; its length corresponds to that 

 of the sternum. The posterior mediastinum is an irregular triangular space, 

 running parallel with the vertebral column; the organs contained in it are evident 

 from Fig. 389, in which the left lung and the heart are lifted out of the thorax 

 and laid to the right and the lateral wall of the posterior mediastinal space 

 is dissected away. The arch of the aorta curves over the left bronchus ; the 

 oesophagus forms a spiral around the aorta; to the right of the descending 

 aorta is the Vena azygos, to the left the Vena licmiazygos. Between the Vena azygos 

 and aorta is the thoracic duct, Ductus thoracicns (see Fig. 388), which ascends 

 behind and to the left of the oesophagus, to terminate at the angle of junction 

 of the left subclavian and internal jugular veins. 



