HEART. 



379 



enter the right, and the four pulmonary veil 

 m>s into the left auricle. The apex of tl 



veins 



apex of the 

 heart is in general formed by the left ventricle 

 alone. The base of the ventricles is cut ob- 

 liquely from before backwards and from above 

 downwards, and this explains how the anterior 

 surface of the ventricles should be longer than 

 the posterior. I have found the difference of 

 length between the two surfaces in a consi- 

 derable number of uninjected hearts to vary 

 from half an inch, or rather less, to an inch. 

 There is little difference between the length of 

 the two ventricles in the uninjected heart. In 

 the injected heart the anterior wall not only 

 becomes elongated but much more convex, 

 while the posterior wall is simply elongated, 

 so that the difference in length between the 

 anterior and posterior surfaces becomes in- 

 creased. This change is more marked in the 

 right ventricle than in the left. Cruveilhier 

 slates that he found the anterior surface of the 

 left ventricle to exceed the posterior by nine or 

 ten lines, and the anterior surface of the right 

 to exceed the posterior by fifteen lines. These 

 measurements have evidently been taken from 

 injected hearts. On the surface of the heart, 

 but more particularly upon the anterior surface 

 of the right ventricle, a white spot, varying in 

 size, is frequently observed. According to 

 Baillie it is placed on the free or inner surface 

 of the external serous membrane.* These spots 

 are so common an appearance that it is some- 

 what difficult to believe that they are morbid. 

 It is, however, very probable that they are the 

 result of some inflammatory action. 



Except in very emaciated subjects there is a 

 greater or less quantity of fat occupying the 

 auricular and ventricular grooves. This fat is 

 generally in greater abundance in old subjects 

 than in young, in accordance with the general 

 law, that the adipose tissue in young persons 

 is principally collected on the surface, and in 

 old persons around the internal organs. When 

 in greater quantity, it is deposited along the 

 ramifications of the coronary vessels, and may, 

 in cases of great obesity, almost completely 

 envelope the surface of the heart. It is gene- 

 rally placed in greater quantities on the right 

 side than on the left. 



The human heart may be considered as con- 

 sisting of two distinct hearts separated from 

 each other by a fleshy septum, and which in 

 the adult have in general no communication. 

 The position of the fleshy septum separating 

 the ventricles is marked by the ventricular 

 grooves. Each heart consists of an auricle and 

 ventricle which communicate by a large orifice. 

 The right heart is occasionally termed the pul- 

 monic heart, from its circulating the blood 

 through the lungs ; and as it circulates the 

 dark blood it was termed the cceur a sang noir 

 by Bichat. The left is occasionally called sys- 

 temic hearty as it circulates the blood through 



* In three hearts in which I carefully examined 

 these white patches, I could distinctly trace the 

 serous membrane over them. See the observations 

 of M. Bizot (Memoires de la Societe Medicale 

 d'Observation de Paris, torn. i. p. 347, 1836,) on 

 these spots. 



the body generally, and is the caur a sang rouge 

 of Bichat. The auricles, from their immediate 

 connexion with the large veins of the heart, 

 sometimes receive the name of venous portion 

 of the heart (pars cordis venosa) ; and in the 

 same manner the term arterial portion of the 

 heart (pars cordis arteriosa) has been applied 

 to the ventricles from their connexion with the 

 large arteries. In describing the different ca- 

 vities of the heart we shall take them in the 

 order in which the blood passes through them. 



Right auricle (auricula dextra vel infer ior t 

 atrium venarum cava rum). External surface. 

 To see the external form of the auricles pro- 

 perly it is necessary that they be first filled 

 with injection. The right auricle is of an irre- 

 gular figure, having some resemblance to a 

 cube, and occupies the anterior, right, and in- 

 ferior part of the base of the heart. It receives 

 all the systemic venous blood of the body. 

 Its inferior portion rests upon the diaphragm. 

 Its largest diameter runs in a direction from 

 behind forward, and from right to left. It is 

 broadest posteriorly, becoming narrow and pro- 

 longed anteriorly, where it terminates in a 

 small and free appendix, which, from its re- 

 semblance to the external ear of the dog, has 

 been termed auricle. This appendix is gene- 

 rally serrated on the edges, more particularly 

 on the external, and projects between the aorta 

 and the upper and anterior margin of the right 

 ventricle. To this smaller portion the term 

 proper auricle has been given, while the larger 

 portion has been called sinus venosus. This 

 division of the auricle into proper auricle and 

 sinus venosus is more distinct in the left than 

 in the right auricle. The posterior surface of 

 the right auricle is connected with the entrance 

 of the two cavae ; its inferior with the base of 

 the right ventricle ; its internal with the left 

 auricle; its outer surface is free; and anteriorly 

 it is prolonged into the proper auricle. The 

 junction of its internal surface with the cor- 

 responding surface of the opposite auricle is 

 marked by an indistinct groove, which cor- 

 responds to the attachment of the septum sepa- 

 rating the two auricles. Its external surface is 

 placed on a plane internal to the outer edge of 

 the right ventricle. 



Internal surJ'ace.^-The inner surface of the 

 right auricle can be satisfactorily examined only 

 when it is opened in situ. Its interior can be 

 best exposed by making a longitudinal incision 

 from the appendix to the orifice of the inferior 

 cava, then opening the superior cava along its 

 anterior surface and connecting the two inci- 

 sions. The inner aspect of the right auricle 

 presents four surfaces: 1. a posterior, where 

 the two venae cavae enter; 2. an outer, upon 

 which numerous muscular bands are seen 

 standing in relief; 3. an internal, which is 

 nearly smooth, forms the septum between the 

 two auricles, and presents an oval depression, 

 about the size of the point of the finger, called 

 the fossa ovalis ; 4. an anterior, formed by the 

 appendix, and which also presents numerous 

 muscular bundles. The superior or descend- 

 ing vena cava enters at the upper and posterior 

 angle, the inferior or ascending cava at the 

 2 Q 2 



