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N euro- Muscular Structures in the Heart. 



By A. F. Stanley Kent, M.A. Oxon., Professor of Physiology, University of 



Bristol. 



(Communicated by Prof. C. S. Sherrington, F.E.S. Received July 25,— 

 Read November 20, 1913.) 



(From the Physiological Laboratory of the University of Bristol.) 



The fundamental fact of the existence of a muscular connection between 

 auricle and ventricle in the mammalian heart was established in 1892 (5, 6). 

 The details of the particular connection first studied were worked out during 

 the years following (1, 3, 7, 8, 13, 15), and attention was directed so com- 

 pletely to the auriculo-ventricular bundle itself that additional ties between 

 auricle and ventricle at other points remained relatively neglected. Partly 

 in result of this, though partly in result of experiments which have been 

 perhaps imperfectly understood, an impression has gained ground (2, 14) that 

 apart from the originally described auriculo-ventricular bundle there exists 

 no other conducting path capable of transferring the state of activity from 

 auricular muscle to ventricular, or vice ' versd. This impression has, indeed, 

 been put forward as an actually ascertained fact (10). 



For some years, however, a mass of facts has been accumulating difficult 

 to explain on the supposition that the conduction between auricle and 

 ventricle consists of one single path alone. The facts can, on the other 

 hand, be explained satisfactorily if there be granted the existence of an 

 auriculo-ventricular connection which is multiple. 



These facts have become known partly as the result of clinical experiences 

 and partly as the result of direct experiment, and are so definite that it is 

 necessary for any satisfactory theory of the cardiac mechanism to take 

 account of them. 



The clinical experiences referred to fall into two categories : — 



A. Cases in which the auriculo-ventricular sequence was found to be 

 normal, though the bundle was destroyed (4, 11) ; and 



B. Cases in which the auriculo-ventricular sequence was abolished, though 

 the bundle was intact (4, 9, 12). 



There are in the literature several cases illustrating each of these condi- 

 tions, and the conclusion is becoming more and more firmly established, that 

 the normal auriculo-ventricular sequence may exist with a destroyed bundle, 

 and that the sequence may be disturbed, or abolished, the bundle remaining 

 unaffected. 



