600 



HEART. 



pointed out in describing the interior of the 

 right auricle, is also intimately connected with 

 the peculiarities of foetal life. It was discovered 

 by Eustachius about the middle of the six- 

 teenth century, who contented himself by point- 

 ing out its position. Little attention was paid 

 to it until the commencement of the eighteenth 

 century, when it was more particularly brought 

 into notice by Boerhaave and Lancisi, who 

 published a new edition of the works and 

 plates of Eustachius, which had then become 

 very scarce. Lancisi supposed that this valve 

 prevented the blood of the superior cava from 

 falling with too much force upon the column 

 ascending by the cava inferior. Winslow,* 

 finding it only perfect in the foetal state, and 

 having cause to believe that its diminution kept 

 pace with the increase of the valve of the 

 foramen ovale, was led to adopt the opinion 

 that its presence had a special reference to that 

 state, and believed that it not only served to 

 break the current of the superior cava as stated 

 by Lancisi, but also opposed the regurgitation 

 of the blood of the auricle into the inferior 

 cava. In the absence of this valve he supposed 

 there would arise two inconveniences in the 

 fcetus the imperfect intermixture of the con- 

 tained blood, and the regurgitation of the blood 

 of the umbilical vein into the placenta. Senacf 

 believed that the Eustachian valve can have no 

 effect in preventing the blood of the cava supe- 

 rior from falling upon the current ascending by 

 the cava inferior, and that it must direct a part 

 of the blood of the cava inferior through the 

 foramen ovale. SabatierJ more particularly 

 pointed out that from the position of this valve 

 passing from the anterior and left part of the 

 vena cava inferior to the left side of the foramen 

 ovale, and from the situation of the foramen 

 ovale at the inferior part of the auricle, the 

 blood of the cava inferior must be directed 

 through the foramen ovale; and further, from 

 the difference in the direction of the two cavae 

 themselves the superior looking downwards, 

 forwards, and to the left side, while the inferior, 

 though it is also slightly directed to the left, 

 passes at the same time upwards and back- 

 wards, when combined with the upper thick 

 margin of the foramen ovale it would neces- 

 sarily happen that the blood of the superior 

 cava must fill the right auricle. 



In three injections of the fcetal circulation 

 which I performed, where arrangements were 

 made to imitate, as far as possibly could be 

 done, the manner in which the two currents 

 flow into the heart during the life of the foetus, 

 results were obtained confirmatory of the opi- 

 nion of Sabatier. This arrangement cannot 

 of course exist in the early months of uterine 



* Mcmoires de 1'Acad. Roy., annee 1717. 



t Op. cit. torn. i. p. 228. 



j Traite complet d'Anatomie, torn. ii. p. 224. 



$ Edinburgh Medical and Surgical Journal, 1835, 

 These injections are also confirmatory of one made 

 by Kilian, where the fluid thrown along the aorta 

 passed to the head and superior extremities, and 

 that along the pulmonary artery to the lower part 

 of the body. 



life from the imperfect developement of the 

 heart itself, and in all probability part only of 

 the blood of the inferior cava is transmitted 

 through the foramen ovale into the left side of 

 the heart for a short time before birth. The 

 pulmonary veins appear to bring very little 

 blood to the left side of the heart until the time 

 approaches that the fcetus must necessarily 

 assume an independent existence. The circu- 

 latory apparatus becomes gradually prepared 

 for this change ; the Eustachian valve begins 

 to shrink, the foramen ovale to diminish in size, 

 and a greater quantity of blood is transmitted 

 through the lungs. Billard* has ascertained 

 from the examination of the bodies of a great 

 number of infants who died within a few days 

 after birth, that the foramen ovale and the other 

 circulatory passages peculiar to the fcetus are 

 generally shut about the eighth day after birth. 

 In nineteen infants who had lived only one 

 day the foramen ovale was completely open in 

 fourteen ; in two it had commenced to become 

 obliterated, in the remaining two it was com- 

 pletely shut. On the subsequent days the 

 number of those with the foramen shut con- 

 tinued to increase; and in twenty examined, 

 who had died on the eighth day, five only had 

 the foramen open. 



PHYSIOLOGY OF THE HEART. 

 Mode of action of the valves of the heart. 

 While the blood is rushing through the auri- 

 culo-ventricular openings during the contrac- 

 tion of the auricles, the lips of the mitral and 

 tricuspid valves are separated from each other 

 and thrown outwards from the axis of the 

 opening, and the larger lip of both is at this 

 time carried towards the arterial orifices. It 

 has generally been supposed that the mitral and 

 tricuspid valves are, during the systole of the 

 ventricles, passively floated up towards, and 

 obstruct the auriculo-ventricular orifices so as 

 to prevent the free regurgitation of the blood 

 into the auricles ; and that the use of the cordae 

 tendinese is merely to limit the movements of 

 the valves, to permit them to be raised suffi- 

 ciently to close the orifices, but at the same 

 time to provide against the otherwise unavoid- 

 ably fatal consequences that would result from 

 these unresisting valves being carried through 

 into the auricles by the current of blood. Mayo, 

 Bouillaud, and others have, however, main- 

 tained that the lips of these valves are not 

 approximated in the mechanical manner just 

 stated, but by the contraction of the musculi 

 papillares of which the cordae tendinese are the 

 proper tendons. As the musculi papillares 

 contract along with the other fibres of the ven- 

 tricles, the lips of the valves are drawn towards 

 the axis of the opening, and are closely applied 

 to each other, forming a kind of cone, the apex 

 of which projects downwards into the ven- 

 tricles. It is from the adoption of these views 

 that Bouillaud proposes to call these musculi 

 papillares, the tensor, elevator, or adductor 

 muscles of the valves. That the lips of the 



* Traite des Maladies des Enfans nouveau-nes, 

 &c., p. 557, 1828. 



