THORACIC CAVITY 



79 



the pulmonary artery. Its position is marked on the surface 

 by a line extending from the lower border of the second 

 left to the upper border of the third right costal cartilage, 

 commencing and terminating 13 mm. (about half an inch) 



FIG. 34. The relations of the Heart and of its Orifices to the Anterior 

 Thoracic Wall. (Young and Robinson. ) 



I to VII. Costal cartilages. 



A. Aorta. 

 Ao. Arch of Aorta. 



C. Clavicle. 

 LA. Left atrium. 

 LV. Left ventricle. 



M. Mitral orifice. 



P. Pulmonary orifice. 



RA. Right atrium. 



RV. Right ventricle. 



SVc. Superior vena cava. 



T. Tricuspid orifice. 



from the margins of the sternum. The right border is formed 

 entirely by the right atrium, and its position is indicated on 

 the surface by a line, convex to the right, commencing above 

 at the upper border of the third right costal cartilage 13 mm. 

 (half an inch) from the side of the sternum, and terminating 

 below at the sixth right cartilage 13 mm, (half an inch) from 



