The Heart. 



365 





410. Position of the 

 heart in the thorax, 



viewed from in front. 



(The level of the diaphragm un moderate expiration is shown hy the black dotted line: the 

 outlines of the heart are indicated in red.) (In part after W. Braune.) 



The heart (cor) is an almost wedge-shaped, hollow, muscular body. It lies asym- 

 metrical to the median plane in the thorax, so that the smaller part belongs to the right 

 half of the body and the larger part of it to the left. The basis cordis (base of the heart) 

 formed by the atria is directed backward and somewhat to the right, the apex cordis (apex 

 of the heart) (belonging to the left ventricle alone) looks forward and to the left and comes 

 into direct contact with the wall of the thorax in the 5tli intercostal space, somewhat medial 

 from tiie costocartilaginous junction. The ostium arteriosum dextrum (0. T. pulnionaiy orifice) 

 lies usually at the sternal end of the 3"d left intercostal space, or behind the 3rci costal cartilage ; 

 the ostium arteriosum sinistrum (0. T. aortic orifice) lies somewhat more medianward and 

 downward, close below the middle of the left halt of the iernum at the level of the 3rd inter- 

 costal space. The middle point of the ostium venosum deictrum (0. T. right auriculoventricular 

 opening) Hes behind the right half of the sternum at' the level of the sternal end of the 

 4tii intercostal space: the ostium venosum sinistrum (0. T. left auriculoventricular opening) 

 lies behind the sternal end of the Si^d left intercostal s-pace. 



Spalteholz. Atlas. 24 



