

THORACIC CAVITY 75 



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 and right, or atrial portion, and a lower and 

 left, or ventricular portion by an oblique sulcus, called the 

 coronary sulcus (O.T. auricula-ventricular) (Figs. 33, 39), which 

 is quite distinct below and on the right, but is masked above 

 and to the Jeft by the roots of the pulmonary artery and the 

 aorta. The position of the coronary sulcus can be indicated 

 on the surface of the body 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, terminating on the left and below 

 in the apex of the heart, which lies posterior to the fifth left 

 intercostal space or to the left sixth rib, 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 

 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 (Fig. 33), 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, called the sulcus 

 terminalis. If the heart is pulled a little over to the left, this 

 sulcus can be traced downwards, along the lateral aspect of 

 the right atrium, to the anterior aspect of the upper end of 

 the inferior vena cava. It indicates the separation between 



