592 



HEART. 



This arrangement of the external fibres was 

 also well known to Winslow* and Lancisi.f 

 Winslow, however, denied that they described 

 the figure of eight, as stated by Lower. More 

 lately Gerdy has given a description of this 

 arrangement, to which he has added an en- 

 graving, which approaches more to the ap- 

 pearance of the perfect figure of eight than 

 that given by Lower. I, however, prefer that 

 given by Lower, as it more nearly resembles 

 the arrangement which I have myself seen in 

 tracing these fibres. A small part of the right 

 and posterior side of this vortex is formed by 

 fibres from the posterior surface of the left 

 ventricle, and from that part of the posterior 

 surface of the right ventricle near the septum, 

 and are attached above to the auricular tendi- 

 nous rings, while the whole of the anterior and 

 left side of the vortex is formed by fibres from 

 the anterior surface and right margin of the 

 ventricles. On tearing these last fibres, which 

 form the principal part of the apex, from the 

 anterior surface of the left ventricle, we find, 

 as we proceed upwards, that a comparatively 

 small part of them cross the anterior fissure 

 upon the right ventricle to reach the right au- 

 ricular tendinous ring. The greater number 

 dip in at the anterior longitudinal fissure, and 

 we shall afterwards find that they can be traced 

 to the base of the septum of the ventricles. 

 By tearing off these fibres downwards, we open 

 into the apex of the left ventricle. A general 

 notion of the manner in which these fibres, 

 passing from the base of the septum, turn in 

 at the apex, and proceed upwards on the inner 

 surface of the left ventricle, may be obtained 

 from Jig. 273. To have been quite accurate 

 the inner fibres should have been more scat- 

 tered, and some of them represented as termin- 

 ating in the columnae carneae. By unravelling 

 the fibres which form the apex, we may open 

 into the interior of the left ventricle without 

 breaking a single muscular fibre. Having thus 

 opened the apex of the heart, although the 

 point is removed, the circular edge is left entire 

 (fig- 274, a), and is formed of another series 



* Memoires de 1'Acad. Roy. 1711. p. 197. 

 t De Motu Cordis : Opera omnia. torn. iv. p. 96. 

 1745. 



of fibres, which, like those taken away, ad- 

 vance spirally from the base to the apex, and 

 turning over the edge (fig. 274, b} ascend in 

 the opposite direction, continuing their course 

 after being reflected. " Proceeding in the 

 same manner the whole apex of the left ven- 

 tricle may be removed, and the same principle 

 of arrangement is found throughout the whole 

 heart even to the base. When we get down as 

 far as the apex of the right ventricle, although 

 the principle remains the same, its effects are 

 more complicated, as it applies to two cavities 

 instead of one." I have frequently satisfied 

 myself of the correctness of the description 

 contained in this passage, which I have quoted 

 from the manuscript of Dr. Duncan. This is 

 the same kind of arrangement which, we have 

 already stated, has been insisted upon by 

 Gerdy, but which we believe can be more 

 satisfactorily seen by tracing the fibres in this 

 manner. Gerdy lays it down as a general law, 

 that all the fibres of the heart form loops, the 

 apices of which look towards the apex of the 

 heart (fg. 271). I find that Dr. Duncan 

 states that while the apices of those loops 

 which form the lower part of the heart point 

 to the apex, as Gerdy has described, " yet he 

 commits a great error when he asserts that the 

 apices of all the fibres of the heart point in 

 that direction, since the number of tops which 

 point in the opposte direction is not less." * 

 When the superficial fibres of the heart have 

 been removed as represented in Jig. 274, we 

 will find that if we trace the great mass of 

 fibres occupying the lower and middle part of 

 the left ventricle, they will be seen to run 

 spirally in strong bundles from above down- 

 wards and from right to left, to wind round 

 and form the posterior as well as the anterior 

 part of the point of the heart; that the greater 

 mass pass in at the apex of the left ventricle to 

 assist in forming the columnae carneae and in- 

 ternal suiface, while others pass in at the apex 

 of the right ventricle, and others again, after 

 turning a little upwards, dip into the interior 

 below some of the higher fibres. On tracing 

 them upwards, on the other hand, they dip in 

 at the anterior longitudinal fissure (fig. 274, d) 

 where they are as it were dovetailed with other 

 fibres from the anterior surface of the right 

 ventricle passing in at the same fissure, and 

 then mount almost vertically upwards to the 

 base of the septum, forming part of the sep- 

 tum of the right ventricle, only separated from 

 its lining membrane by a thin layer of fibres, 

 and are inserted in a strong band in the ox 

 into the bone of the heart, which is placed 

 between the auriculo-ventricular openings and 

 aorta, while in the human heart they are spread 



* I could not discover in Dr. Duncan's manu- 

 script any other description or allusion to the fibres 

 here mentioned whose arrangement is opposed to 

 the general law which Gerdy is anxious to establish. 

 There is no doubt, however, that many of these 

 loops at the base are principally directed to the 

 periphery of the organ, and very little downwards, 

 and that a few in the infundibulum are slightly 

 directed upwards. 



