THORACIC CAVITY 



95 



sion, the fossa ovalis, which is bounded anteriorly and above 

 by a muscular ridge, the limbus ovalis, whilst below and 

 posteriorly it fades away into the orifice of the inferior 

 vena cava. 



The floor of the fossa ovalis is thin ; it marks the situa- 



Second costal cartilage Sternum Internal mammary vessels 



lavity of left pleura - 



Left lung 

 (upper lobe) 



Lymph glands- 

 Arch of aorta ^ ^-^- : 



Left phrenic nerve 

 Left vagus nerve 

 eft recurrent nerve 



Lymph glands 

 Thoracic duct 



jrcostal vessels 



y of left pleura 

 ercostal vessels 

 ing (lower lobe) -- 



Pectoralis major 

 Right pleural cavity 



Remains of thymus 



-Right phrenic nerve 

 Superior vena cava 



Lymph glands 



-Trachea 

 Right vagus nerve 



-jp Oesophagus 



Intercostal vessels 



Fourth thoracic 

 vertebra 

 - Intercostal artery 



Cavity of right pleura 



FIG. 47. Transverse section of the Thorax of a Male Adult 

 along the plane B-B, Fig. 46. 



tion of the lower part of the boundary of the foramen ovale 

 of the foetus, and is formed by a portion of the interatrial 

 wall which, in the foetus, acted as a flap valve and prevented 

 regurgitation of blood from the left to the right atrium. 



Vena Cava Superior. The superior vena cava returns to 

 the right atrium the venous blood from the head and neck, 



