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The nerves of the atrio-ventricular bundle

Physiologists, in explaining the transmission of the wave of contraction on the heart from atrium to ventricle, have alternately leaned towards either the myogenic or the neurogenic hypothesis. Many of the discussions on this subject have been useless and many of the deductions false, because of the...

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Bibliographic Details
Published in:Proceedings of the Royal Society of London. Series B, Containing papers of a biological character Containing papers of a biological character, 1909-04, Vol.81 (546), p.151-164
Main Author: Wilson, J. Gordon
Format: Article
Language:English
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Summary:Physiologists, in explaining the transmission of the wave of contraction on the heart from atrium to ventricle, have alternately leaned towards either the myogenic or the neurogenic hypothesis. Many of the discussions on this subject have been useless and many of the deductions false, because of the misconception of the anatomical facts. For long it was held that through in cold-blood vertebrates the experiments of Gaskell had settled the question in favour of the myogenuc theory, yet in mammals there existed an interruption between the atrial muscle and the ventricular muscle at the atrio-ventricular groove, and that this was opposed to a general acceptance of the myogenic theory. Later anatomical investigation, however, has definitely shown that there exists in all mammals, between the ateria and the ventricles, a pathway of modified muscle fibres along which the contraction wave appears to go. This is the atrio-ventricular (auriculo-ventricular) bundle, or bundle of His. The discovery of this muscular connection gave very decided support to the myogenic hypothesis, and at present it would appear that prevailing opinion favours this theory. It receives additional support in so far that in this bundle only a few nerve fibres have as yet been recognised by one or two observers; some assert that nerves are not present, or, if so, are too few in number to be of any movement. More definite statements gave been made by Tawara and Retzer. Tawara (1) found that “in the heart of the calf the atrio-ventricular bundle is accompanied by a very considerable nerve bundle, which runs with the muscle bundle, and in the left ventricular septum nerve cells are present 1·2 cm. below the aortic valve.” In the atrio-ventricular bundle of the sheep only a few nerve bundles were seen, but in the dog, cat, and in man he could find none, though he expressly states that these cannot be excluded, since, fine nerve fibres accompany the bundle. Retzer (2) has pointed out that the first ganglion cells that appear in the embryonic heart lie in the atrial septum, immediately above the beginning of the conductive system; further, that the Prukinje fibres are surrounded by a plexus of non-medullated nerves.
ISSN:0950-1193
2053-9185
DOI:10.1098/rspb.1909.0015