APPENDIX TO CHAPTER XIII. 



11. Open the right ventricle by passing the blade of a scalpel 

 through the heart about an inch from the upper border of the ventri- 

 cle, and on the right of the band of fat marking externally the limits 

 of the ventricles, and noted above (9, b\ and then cut down towards 

 the apex, keeping on the right of this line; cut off the pulmonary 

 artery about an inch above its origin from the heart, and open the 

 right auricle by cutting a bit out of its wall, to the left of the 

 entrances of the vense cavae. On raising up by its point the wedge- 

 shaped flap cut from the wall of the ventricle, the cavity of the latter 

 will be exposed. 



a. Pass the handle of a scalpel from the ventricle into the auricle, 

 and also from the ventricle into the pulmonary artery, and make out 

 thoroughly the relations of these openings. 



b. Slit open the right auricle. Observe the apertures of the vena 

 cavtz, and note that the pulmonary veins do not open into this 

 auricle. % 



12. Raise up by its apex the flap cut out of the ventricular wall, 

 and if necessary prolong the cuts more towards the base of the 

 ventricle until the divisions of the tricuspid valve come into view. 



a. Note the muscular cord (not found in the human heart) stretch- 

 ing across this ventricle. Also the prolongation of the ventricular 

 cavity towards the aperture of the pulmonary artery. 



b. Cut away the right auricle, and examine carefully the tricuspid 

 valve, composed of three membranous flexible flaps, thinning away 

 towards their free edges: proceeding from near these edges are 

 strong tendinous cords (chorda tendinece), which are attached at their 

 other ends to muscular elevations (papillary muscles} of the wall of 

 the ventricle. 



c. Slit up the right ventricle until the origin of the pulmonary ar- 

 tery comes into view. Looking carefully for the flaps of the semilunar 

 valves, prolong your cut between two of them so as to open the bit of 

 pulmonary artery still attached to the heart. Spread out the artery 

 and examine the valves. 



d. Each flap makes, with the wall of the artery, a pouch, opposite 

 which the arterial wall is slightly dilated. The free edge of the valve 

 is turned from the heart, and has in its middle a little nodule (corpus 

 A ran tif). 



13. Open the left ventricle in a manner similar to that employed 

 for the right. Then open the left auricle by cutting a bit out of its 

 wall above the appendage. Cut the aorta off about half an inch 

 above its origin from the heart. The aperture between left auricle 

 and left ventricle can now be examined; also the passage from the 

 ventricle into the aorta, and the entry of the pulmonary veins into 

 the auricle; and the septum between the auricles and that between the 

 ventricles. 



a. Pass the handle of a scalpel from the ventricle into the auricle; 

 another from the ventricle into the aorta; and pass also probes into 

 the points of entrance of the pulmonary veins. Observe that no other 

 veins open into the left auricle. 



b. Note the great thickness of the wall of the left ventricle, as com- 

 pared with that of the right ventricle or of either of the auricles. 



