Two clinical lectures / by Alexander Morison.

  • Blackhall-Morison, Alexander, 1850-1927.
Date:
1901
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Licence: In copyright

Credit: Two clinical lectures / by Alexander Morison. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    the distinction between a noise and a tone is merely one of vibration, and the fluid medium—the blood—is that to which such vibration must in greatest measure be communicated, the important part played by the blood itself in the production of the first sound of the heart appears on clinical grounds to be unquestionable. The last point which has to be weighed—namely, the influ- ence of the thorax, the air-containing cavity which holds the heart—in producing the first sound, is easily disposed of. Mr. Grant's case already quoted proves not only that the chest wall has little or nothing to do with the production of the sounds of the heart, including the first sound, but also reveals another very interesting fact—namely, that both sounds may be clearly audible in cases of ectocardia at the base of the heart, when the apex from its mobility is incapable of being satisfactorily auscultated. Were it possible to place the whole mechanism in vacuo without the heart ceasing to pulsate, no doubt all sound to the ear would be abolished, very much as the movements of a watch would cease to be audible under like circumstances. But the general question of the conductive power of air may be dismissed as foreign to the present inquiry. In Brakyn's 1 apparatus air took the place of blood and emitted the systolic and diastolic sounds. In nature blood takes the place of air. The conclusion, therefore, which appears to flow from this clinical study of the question seems to be that the impulse given to the blood by the muscular action of the heart gives rise in it and in the vibratory structures containing it, to vibrations of a certain quality which result in that tone which is synchronous with cardiac systole and usually called the first sound of the heart, and that the largest share in this result must be attributed to vibrations in the blood itself, to produce which at a normal 1 The ' Lancet,' November, 1849.
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