278 THE CIRCULATORY SYSTEM. 
(i.e., it lies against the septum), while of the two others which 
do not lie against the septum, one is dorsal (¢”’) and the other 
ventral. Each flap is thin, semicircular, and membranous, and 
is attached to the border of the auriculoventricular opening by 
the diameter of the semicircle. The free border of each is 
attached to the wall of the heart by numerous delicate ten- 
dinous bands, the chorde tendinee (c), some of which are 
attached to the lower face of each valve. The chorde tendinez 
b 
Fic. 117.—HEarT, WITH RIGHT VENTRICLE LAID OPEN TO SHOW THE TRI- 
CUSPID VALVE. 
a, trabeculz; 4, columnze carneze; ¢, chord tendiner; @, d’, d”, the three flaps 
of the tricuspid valve; e, aorta; 7, conus arteriosus, laid open; g, semilunar valves 
of the pulmonary artery. © 
of the septal valve (or most of them) are attached at their 
opposite ends to the septum directly, while those of the dorsal 
and ventral flaps are attached to the ends of three or more 
band-like muscles, columne (or trabeculze) carnee (4), which 
are fixed by their opposite ends to the ventricular wall. 
Between the conus arteriosus (/) and the pulmonary artery 
are three pocket-like semilunar valves (Fig. 117, ¢), one ven- 
tral, one dextral, and one sinistral. Between each valve and 
the wall of the pulmonary artery there is an enlargement of the 
cavity of the artery, one of the pulmonary sinuses (or sinuses 
of Valsalva). Beyond the sinuses the pulmonary artery divides 
into right and left branches (Fig. 116, 7). 
