112 



THE H<")RSE IN inOALTH AND DISEASE 



It lia^ orifices fur the antcrinr and postiTior vena cava, and in the 

 A'cnirai part the iii>:ht auri(aili)\'cntricular orifico, which leads 

 intd tl:c liiilit A'cntriclc. Tliis orilicp is "guarded by the tricuspid 

 \"al\'('. B}' means (jf this and the other \'ah'es tlie Ijlood is Icept 

 tiowias in one direction. The right ventricle ociaipies the right 

 antei'ior part of the ventriculai' mass, liiit does not reach tlic apex. 

 It e(jnnnunicates with tlie pulmonary arterj- through the pulmonary 



.Vi chid t. 



}Fir-.i:uh piiliiiaU 



^Tnaispid rnlK 

 'I'" jjllhu-'j tnnsdi 



T i'iih< riiW earner 



V\«. 3s, — Scrtion of licart. Tlic MT'fion is rut nearly ;it right angles to 

 tlic vi'ntrirular septum, and is vicwnl from tlic ri.iiht. iSi-son, Anatomy of 

 Uoiiicstic Animals.) 



orifice, wli!<'h is guarded liy the semilunar \'alve composed of three 

 cus])s. dlie left auricle forms the posterior part of the base of the 

 heart. Seven oi- eight pulmonary A'cins open into this cavity. 

 Below it communicates by the left auriculoventricnlar orifice, 

 whicli is guai'd(>d by the liiiaispid ^ah-e, with the left ventricle, 

 The latter (hscharges blood tlirougli the aortic orifice. This 

 opening is giiartled by the aortic semilunar valve similar to but 

 stronger than the corresponding valve on the right side, AH 



