32 Practicum V. The Right Ventricle. 



the vessel. This part of the ventricle is sometimes distinguished as the 

 CON us. 



b. At a point on the ventricle about i cm. from the artery and in the 

 line of its right border, insert the scalpel-point not more than i cm. and 

 cut sinistrad, at a right angle with the axis of the vessel, for its width, 

 stopping 5-10 mm. from the interventricular furrow. 



c. Then, inserting the scalpel no deeper, cut parallel with the furrow 

 until the right margin of the ventricle is reached near the apex of the 

 heart. 



d. Lift the free corner of the triangular flap so as to get a partial 

 view of the cavity of the ventricle ; look particularly for a cylindrical band 

 connecting the interventricular septum with the lateral wall. 



e. With the scissors cut from the first point of departure on the 

 hypothenuse of the triangle, swerving a little to the left if necessary to 

 avoid the attachment of the band just mentioned ; this may now be seen 

 distinctly ; it is the MODERATOR BAND, constant (though varying in size) 

 in the sheep and some other animals, but infrequent in man. It is sup- 

 posed to limit the distention of the ventricle. 



f. Keep the cut edges of the ventricular wall apart with large pins 

 or with the fingers and sketch the cavity with special reference to the 

 moderator band. 



10. From the caudal or apical end of the triangular opening already 

 made, cut along the left border of the ventricle to within about 2 cm. of 

 the auriculo-ventricular line. 



a. Lift the triangular flap so formed and note that from certain parts 

 of its ental surface, in addition to the moderator band, spring muscular 

 columns (COLUMN^ CARNEY) which extend cephalad and are connected 

 with fibrous cords (CHORDAE TENDINE^E). 



b. From the apex and margins of the flap trim off so much as has no 

 direct connection with the band or columns. 



ii. The Tricnspid Valves. Pass the finger from the auricle into 

 the ventricle and distend the AURICULO-VENTRICULAR ORIFICK. Note 

 that it is surrounded by three fibrous sheets which hang down into the 

 ventricle and are connected at the sides with the cords and columns above 

 mentioned. These are TRICUSPID VALVES or RIGHT AURICULO-VENTRIC- 

 ULAR VALVES ; one lies against the ventricular septum, the others re- 

 spectively near the right and left sides of the ventricle. 



a. The cords are attached mainly at the sides of the valves, hut from the middle of 

 the free border of the septal valve there sometimes pass several cords to a depression in 

 the septum, the columns being wholly short or wholly absent. 



b. Some of the cords from the right of the septal valve may spring from the seplal 

 end of the moderator band. 



12. The parts may be exposed more fully by removing the rest of 

 the lateral wall of the ventricle, a patch being retained, if desired, for the 

 attachment of the moderator band. A still better view may be had by 

 cutting the auriculo-ventricular "ring" with the scissors between the two 

 valves that meet at the right. 



a. The valves permit the ready passage of blood from the auricle to the ventricle but 

 a reflux is checked by the crowding of the valves towards a common point, by a certain 

 portion of blood getting behind them, just as swinging doors may be closed by the pressure 

 brhin<l them of a few individuals, although the crowd as a whole is striving to pass 

 through The columns and cords prevent the free edges of the valves from being carried 

 too far. 



b. In studying the action of the valves on an alinjected heart it should be borne in 

 mind that the distention of the right ventricle by the alcohol is sometimes excessive, and 

 mav prevent the complete closure of the orifice which occurs in life. 



i 13. The Pulmonary Artery. About midway between the ventricle 



