1, the wall of the ventricle cut across; 2, the position of the auriculo-ventricular ring; 3, the wall of the auricle; 4, masses of fat lodged between the auricle and pulmonary artery.
can put your three fingers. This is the opening into the right ventricle; and you will have no difficulty in putting your fingers from the auricle into the ventricle and bringing them out again.
P.A. pulmonary artery, with its semilunar valves; Ao. aorta, do.
R.A.V. right auriculo-ventricular orifice with the three flaps (lv. 1, 2, 3) of tricuspid valve.
L.A.V. left auriculo-ventricular orifice, with m.v. 1 and 2, flaps of mitral valve; b, piece of whalebone passed into coronary vein. On the left part of L.A.V. the section of the auricle is carried through the auricular appendage; hence the toothed appearance due to the portions in relief cut across.
But hold the heart in one hand with the auricle upwards, and try to pour some water into the ventricle. The first few spoonfuls will go in all right, and then you will see some thin white skin or membrane come floating up into the opening and quite block up the entrance from the auricle into the ventricle; the