THE HEART. 



325 



heart's action. At the time of their diastole, the blood enters the 

 cavity of the ventricles through the auricular orifice ; at the time of 

 their systole it is expelled into the arterial trunks. 



Simultaneously with the hardening and contraction of the ventricles 

 the apex of the heart moves slighly from left to right, and rotates at 

 the same time upon its own axis in a similar direction. This movement 

 was also observed by Harvey, who describes it as follows: 1 



" And if any one," he says, u bearing these things in mind, will care- 

 fully watch the motions of the heart in the body of the living animal, 

 he will perceive not only all the particulars I have mentioned, namely, 

 the heart becoming erect and making one continuous motion with its 

 auricles ; but, further, a certain obscure undulation and lateral inclina- 

 tion in the direction of the axis of the right ventricle, the organ twisting 

 itself slightly in performing its work." 



Both these movements, of lateral inclination and rotation, result from 

 the spiral arrangement of the muscular fibres on the exterior of the 



heart. The most superficial of these fibres 

 Fig. 106. start from the base of the organ and pass 



toward its apex, following an obliquely 

 spiral course over its anterior surface, from 

 above downward and from right to left. 

 The contraction of this superficial portion 



Fig. 107. 



BULLOCK'S HEAKT, anterior 

 view, showing the superficial mus- 

 cular fibres. 



CONVERGING SPIRAL FIBRES AT THE APKX 

 OP THE HEART. The direction of the arrows indi- 

 cates that of the rotating movement of the heart at 

 the time of the ventricular systole. 



of the muscular fibres accordingly tilts the apex of the heart in a slight 

 degree bodily from left to right. As the fibres, however, reach the point 

 of the heart they curl round its axis, change their direction, and disap- 

 pear from sight, becoming deep seated and passing upward along the 

 septum and internal surface of the ventricle, to a termination finally in 

 the columnse carneae and the fibrous border of the auriculo-ventricular 

 ring. They thus form, exactly at the apex of the heart, a kind of whorl 

 or vortex, of spiral muscular fibres easily distinguishable when the organ 

 is in active motion. Any muscular fibre arranged in this direction 



Works of William Harvey, M.D., Sydenham Edition. London, 1847, p. 32. 



