d78 RIGHT AURICLE. 



The Auricula-ventricular opening is the large opening of commumca - 

 tion between the auricle and ventricle. 



The Eustachian* valve is a part of the apparatus of foetal circulation, 

 and serves to direct the placental blood from the inferior cava, though the 

 foramen ovale into the left auricle. In the adult it is a mere vestige and 

 imperfect, though sometimes it remains of large size. It is formed by a 

 fold of the lining membrane of the auricle, containing some muscular 

 fibres, is situated between the opening of the inferior cava and the auriculo- 

 ventricular opening, and is generally connected with the coronary valve. 



The Coronary valve is a semilunar fold of the lining membrane, stretch- 

 ing across the mouth of the coronary vein, and preventing the reflux of 

 the blood in the vein during the contraction of the auricle. 



The Jlnnulus ovalis is situated on 

 the septum auricularum, opposite the 

 termination of the inferior cava. It 

 is the rounded margin of the septum, 

 which occupies the place of the fora- 

 men ovale of the foetus. 



The Fossa ovalis is an oval de- 

 pression corresponding with the fora- 

 men ovale in the foetus. This opening 

 is closed at birth by a thin valvular 

 layer, which is continuous with the 

 left margin of the annulus, and. is 

 frequently imperfect at its upper part. 

 I The depression or fossa in the right 

 auricle results from this arrangement. 

 There is no fossa ovalis in the left 

 auricle. 



The Tuberculum Loweri\ is the 

 portion of auricle intervening between the openings of the superior and 

 inferior cava. Being thicker than the walls of the veins, it forms a projec- 



* Bartholomew Eustachius, born at San Severino, in Naples, was Professor of Medi 

 cine in Rome, where he died in 1570. He was one of the founders of modern anato- 

 my, and the first who illustrated his works with good engravings on copper. 



j- The anatomy of the heart; the organ is viewed upon the right side. 1. The cavity 

 of the right auricle. 2. The appendix auriculas, in the cavity of which the musculi 

 pectinati are seen. 3. The superior vena cava, opening into the upper part of the right 

 auricle. 4. The inferior vena cava. 5. The fossa ovalis ; the prominent ridge sur- 

 rounding it is the annulus ovalis. 6. The Eustachian valve. 7. The opening of the 

 coronary vein. 8. The coronary valve. 9. The entrance of the auriculo-ventricular 

 opening. Between the numbers 1 and 9, two or three of the foramina Thebesii are 

 seen. a. The right ventricle, b. c. The cavity of the right ventricle, on the walls of 

 which the columns carneae are seen; c is placed in the channel leading upwards to the 

 pulmonary artery, d. e. f. The tricuspid valve; e is placed on the anterior curtain, and 

 /, on the right curtain, g. The long columna carnea, to the apex of which the anterior 

 and right curtains of the tricuspid valve are connected by the chordae tendineas. h. The 

 " long moderator band/' i. The two columnas carneoe of the right curtain, k. The at 

 tachrnent by chordae tendinese of the left limb of the anterior curtain. /, I. Chords ten 

 dintce of the "fixed curtain" of the valve, m. The valve of the pulmonary artery. The 

 letter of reference is placed on the inferior semilunar segment, n. The apex of the right 

 appendix auricula?, o. The left ventricle, p. The ascending aorta, q. Its arch, with 

 the three arterial trunks which arise from the arch. r. The descending aorta. 



$ Richard Lower, M. D. " Tractatus de Corde ; item de Motu et Colore Sanguinis," 

 1669 His dissections were made upon quadrupeds, and his observations relate rather 

 to animals than to man. 



