THORAX 



Posterior to its lower part is the trachea (Figs. 28, 29), but 

 as the artery passes upwards and to the right it gains the 

 side of the trachea and has the upper part of the right 

 lung and pleura posterior to it. To its left, at its com- 

 mencement, is the left common carotid artery, and at a 



FIG. 30. The relations of the Heart and of its Orifices to the Anterior 

 Thoracic Wall. 



I to VII. Costal cartilages. 



A. Aortic orifice. 



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 cav 

 T. Tricuspid orifice. 



higher level the trachea. On its right side is the right 

 innominate vein, which separates it from the right phrenic 

 nerve and the pleura. As a rule it gives ofT its terminal 

 branches only, but occasionally a small artery, called the 

 thyreoidea ima, springs from it. 



Arteria Thyreoidea Ima. This artery is frequently absent. When it is 

 present it springs from the innominate artery, or from the arch of the aorta, 

 and runs upwards, anterior to the trachea, to the thyreoid gland. 



