DISSECTION OF HEART 81 



observe the coronary vein 1 opening into it a very short 

 distance from the heart. 



7. Cut away most of the auricle, and holding the 

 ventricle in the left hand, pour water suddenly into the 

 auriculo-ventricular orifice. The right auriculo-ventri- 

 cular or tricuspid valve will float up and close the 

 orifice. Note the star-shaped junction of the valve-flaps. 



8. Introduce a pair of scissors between two of the 

 valves, and cut through the wall towards the apex. 

 Having arrived at the bottom of the ventricular cavity, 

 turn the scissors sharply round and carry an incision 

 at an acute angle with the previous one, alongside the 

 septum, towards, but not into, the pulmonary artery. 

 Lifting up the flap, note : 



The thickness of the ventricular wall, the projections 

 of its inner surfaceorcolumnse carneae, the band of muscle 

 (moderator band) running from wall to wall of the ven- 

 tricle across its cavity. The ventricular cavity does not 

 extend to the apex. 



A pale strip will be seen extending from the top of 

 the moderator band in the direction of the foramen 

 ovale; this is the continuation in the right ventricle of 

 the auriculo-ventricular bundle. Cut through the 

 endocardium and isolate the bundle in its course on the 

 septum. 



The tricuspid valve, its form, and attachment to the 

 auriculo-ventricular ring, the chordae tendinae, and 

 their attachment to the summits of the papillary muscles. 



1 In man, the left azygos vein joins the right, and this runs into the 

 superior vena cava; the coronary vein (coronary sinus) opens direct into 

 the right auricle. 



I.- 6 



