THORACIC CAVITY 53 



The Sterno- costal Surface of the Heart. Before the 

 dissectors disturb the heart, which- has been exposed by the 

 reflection of the anterior wall of the pericardium, they should 

 note carefully not only the parts of the heart which are visible, 

 but also their relations to the anterior wall of the thorax. 

 The latter they can easily do by replacing the sternum and 

 costal cartilages in position from time to time. 



They will find that the sterno-costal surface is divided 

 into an upper, right, or atrial portion and a lower, left, or 

 ventricular portion by an oblique sulcus, the coronary sulcus 

 (O.T. auriculo-ventricular\ which is quite distinct below and 

 on the right, but is masked above and to the left by the 

 roots of the pulmonary artery and the aorta. The position 

 of this sulcus can be indicated on the surface by a line 

 extending obliquely downwards and to the right, from the 

 sternal end of the third left to the sternal end of the sixth 

 right costal cartilage. Below and to the left of the sulcus 

 is the ventricular part of the sterno-costal surface, termi- 

 nating on the left and below in the apex of the heart, which 

 lies posterior to the fifth left intercostal space, three and a half 

 inches from the median plane. The ventricular area of the 

 sterno-costal surface is divided by the anterior longitudinal 

 sulcus (O.T. anterior interventricular sulcus) into a right 

 two-thirds, formed by the right ventricle, and a left third, 

 formed by the left ventricle. The anterior longitudinal 

 sulcus terminates on the lower border of the sterno-costal 

 surface, to the right of the apex, in a slight notch, the indsura 

 cordis. The apex, therefore, is formed entirely by the left 

 ventricle. The lower margin of the sterno-costal surface lies 

 on the diaphragm. It is formed chiefly by the lower border 

 of the right ventricle, and only to a small extent by the apical 

 part of the left ventricle. 



The upper and right portion of the sterno-costal surface is 

 formed by the atria, which are to a large extent concealed by 

 the pulmonary artery and the ascending part of the aorta. 

 Above and to the right is the right atrium, continuous above 

 with the superior vena cava and below with the inferior vena 

 cava, whilst its auricular portion (O.T. auricular appendage) 

 curves upwards and to the left, along the line of the coronary 

 sulcus, to the root of the pulmonary artery. 



Crossing the front of the right atrium, immediately below 

 the lower end of the superior vena cava, is a sulcus, the sulcus 



