328 ZOOTOMY. 



the heart is supplied with blood, situated in two of the aortic 



sinuses of Valsalva. 



XXXVIII. Remove the outer walls of both ventricles, 

 by making first a transverse incision along the 

 base of each, and then taking from its extremities 

 converging incisions nearly to the apex of the 

 heart. Make out ; 



324. The comparatively thin walls of the right ventricle, 

 and the extremely thick walls of the left ventricle. 



325. The septum ventriculorum, or partition between 

 the ventricles ; it is convex towards the right, concave 

 towards the left side, so that, in transverse section, the 

 cavity of the right ventricle appears semilunar, that of 

 the left almost circular. 



326. The columnse carnese, muscular ridges into which 

 the inner surface of the ventricular walls is raised. One 

 of those in the right ventricle usually takes on the form 

 of a cord extending across the cavity from the inner to the 

 outer side, and called the moderator band. 



327. In the right ventricle, the three flaps of the 

 tricuspid valve attached by their anterior edges round 

 the auriculo-ventricular aperture : their irregular posterior 

 edges, which depend into the ventricle, are attached by 

 strings, the chordae tendineae, to small conical elevations 

 of the ventricular wall, the musculi papillares. 



328. In the left ventricle, the two flaps of the mitral 

 valve, attached in the same manner as those of the tricuspid. 

 The papillary muscles are, however, fewer in number and 

 considerably larger in size. 



329. The conus arteriosus, or infundibulum, a pro- 

 longation of the left anterior angle of the right ventricle, in 

 the apex of which is the aperture of the pulmonary artery. 



330. The aperture of the aorta in the left ventricle. 



