416 LABORATORY MANUAL OF HUMAN ANATOMY 



(Vide Fig. 208.) Clean out the cavity of the right atrium with a 



wet sponge. 



Right Atrium (Atrium dextrum) (O. T. Right Auricle). 



Examine the endocardium and the myocardium of its wall, 

 the openings of the V. cava superior, V. cava inferior, and sinus 

 coronarius. Note the subdivision of the right atrium into two 

 parts by the terminal sulcus of the right atrium (sulcus ter- 

 minalis atrii dextri), which corresponds to the terminal crest 

 (crista terminalis) in the interior; the posterior, medial part of 

 the atrium is called the venous sinus (sinus venarum [cavarum] ) . 

 Observe the exact situation of the right auricle (auricula dextra) 

 (O. T. right auricular appendix). In the right atrium, examine 

 also 



(a) Intervenous tubercle of Lower (tuberculum intervenosum [Loweri]). 



(b) Septum of the atria (septum atriorum) (0. T. interauricular sep- 



tum). 



(ba) Membranous part of septum of atria (pars membranacea 



septi atriorum). 



(bb) Oval fossa (fossa ovalis). 



(bba) Edge of oval fossa (limbus fossae ovalis [Vieus- 

 seni]) (0. T. annulus ovalis). 



(c) Valve of inferior vena cava (valvula venae cavae [inferioris Eusta- 



chii]) (0. T. Eustachian valve). 



(d) Valve of coronary sinus (valvula sinus coronarii [Thebesii]) (0. T. 



coronary valve, or valve of Thebesius). 



(e) Venous ostium of right ventricle (ostium venosum) (0. T. right 



auriculoventricular orifice). 



(/) Foramina of the smallest veins (foramina venarum minimarum [The- 

 besii]) (0. T. foramina Thebesii). 

 (g) Pectinate ("comb-like") muscles (Mm. pectinati). 



Right Ventricle (Ventriculus dexter) and Pulmonary Artery (A. pul- 

 monalis) . 



Cut into the right ventricle by a vertical incision half a centi- 

 metre to the right of the sulcus longitudinal is anterior, extending 

 all the way from the conus arteriosus to the facies diaphrag- 

 matica. Make carefully a second incision from the upper end of 

 the first one, transversely to the right, parallel to the sulcus 

 coronarius and one centimetre below it. (Vide Fig. 210.) Avoid 

 injury to the tricuspid valve ; the incision may be controlled by 

 inserting the index-finger of the left hand from the right atrium 

 into the ventricle through the ostium venosum. Reflect the 

 V-shaped flap of the ventricular wall to the right and clean the 

 cavity of the ventricle with a wet sponge. 



