THORACIC CAVITY 



67 



cartilage. It is entirely devoid of any valvular arrangement. 

 Immediately below it on the posterior wall of the atrium, in 

 a well -fixed heart, will be found a rounded prominence, 

 the intervenous tubercle (Lower), which tends to throw the 



Pericardium 



Superior vena cava 



Musculi pectinati 

 Crista terminalis 



Diaphragm 



Vena azygos 



Right 

 onchus 



; Right 



- pulmonary 

 &" artery 



Bronchial 



/ "gland 



!n_ Pulmonary 



veins 



Venous sinus 

 of right atrium 



Inferior vena 

 cava 



Hepatic vein 



FIG. 33. Sagittal section through the Right Atrium of the Heart and 

 the Root of the Right Lung. 



stream of blood entering the atrium by the superior vena 

 cava downwards and anteriorly into the atrio-ventricular orifice. 

 The orifice of the inferior vena cava is in the lower and 

 posterior part of the atrium, at the level of the sixth right costal 

 cartilage and the lower border of the eighth thoracic vertebra. 

 Running along its anterior margin, and intervening between it 

 and the atrio-ventricular opening, is the remnant of a valve, 

 the valve of the vena cava (Eustachian). It terminates, to the 

 left, in the lower end of a muscular ridge, limbus fossa ova/is 



