458 



DISSECTION OF THIO THORAX. 



and apex. 



Interior of 

 appendix. 



Crista 

 terminalis. 



apex is prolonged downwards towards the junction of the auricle 

 with the ventricle, and in it is the opening into the right ventricular 

 cavity. 



The anterior wall is thin and loose. Near the top is an opening 

 leading into the pouch of the appendix, which will admit the tip 

 of the little finger. Near, and in the interior of the appendix, 

 are prominent fleshy bands, named musculi pectinati, which run 

 mostly in a transverse direction, and form a network that contrasts 

 with the general smoothness of the auricle. The musculi pectinati, 

 end upon a common ridge, the crista terminalis. 



The posterior (and inner) watt corresponds mostly with the septum 



Thebesian valve. 

 Opening of coronary sinus 

 Eustachian valve. 



Fossa oval is. 



Annulus ovalis. 



FIG. 168. THE INTERIOR OF THE RIGHT AURICLE (FROM THE FRONT AND 

 RIGHT) ; THE CURVED ARROW POINTS TO THE AURICULO-VENTRICULAR 

 OPENING. 



between the auricles. On it, opposite the opening of the inferior 

 vena cava below, is a large oval depression, the fossa ovalis, which 

 is the remains of an opening between the auricJes in the foetus. 

 A thin semitransparent structure forms the bottom of the fossa ; 

 and there is oftentimes a small oblique aperture into the left 

 auricle at its upper part. Around the upper three-fourths of the 

 fossa is an elevated band of muscular fibres, called annulus ovalis, 

 which is most prominent above and on the left side, and gradually 

 subsides below. 



Apertures of At the lower end of the posterior wall, between the inferior 

 caval and the auriculo-ventricular orifices, is the aperture of the 



Fossa 

 ovalis. 



Annulus 

 ovalis. 



