A textbook of human physiology / translated from [the] 6th German edition by W. Stirling.

  • Landois, Leonard
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: A textbook of human physiology / translated from [the] 6th German edition by W. Stirling. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    115/980 page 63
    ah. Thus, the long diameter of the ellipse (FG) is diminished, the small diameter <lc is increased, while the base is brought nearer to the chest-wall e. This alone Fig. 39. Curves from the apex-beat. A, normal curve (man); B, from a dog ; C, very rapid curve (dog) ; D and E, normal curves (man) registered on a vibrating glass plate where each indentation = 0 01613 sec. In all the curves a5 means contraction of the auricles, and be of the ventricles ; d, closi;re of the aortic, and e, of the pulmonary valves ; ef, diastole of the ventricle. does not cause the impulse, but the basis of the heart, being hardened during the systole and brought nearer to the chest-wall, allows the apex to execute the move- ment which causes the impulse (p. 61). (2) During relaxation, the ventricle lies with its apex (fig. 40, II., i) obliquely downwards, and with its long axis in an oblique direction—so that the angles (hci, aci) formed by the axis of the ventricles with the diameter of the base are unequal —during systole it represents a regular cone, with its axis at right angles to its base. Hence, the apex (i) must be erected from below and behind (p), forwards and upwards {Harvey— cor sese erigere ), and when hardened during systole presses itself into the intercostal space (fig. 40, II.). (3) The ventricles undergo during systole a slight spiral twisting on their long axis (lateralem inclinationem—Harvey), so that the apex is brought from behind more forward, and thus a greater portion of the left ventricle is turned to the front. This rotation is caused by the muscular fibres of the ventricles, which proceed from that part of the fibrous rings between the auricles and ventricles which lies next the anterior thoracic wall. The fibres ])ass from above obliquely downwards, and to the left, and also run in part upon the posterior surface of the ventricles. When they contract in the axis of their direction, they tend to raise the apex, and also to bring more of the posterior surface of the heart in relation with the anterior thoracic wall. It is favoured by the slightly spiral arrangement of the aorta and pulmonary artery. These are the most important causes, but the minor causes are, (4) The reaction impulse or i-ecoil, or that movement which the ventricles are said to undergo, (like an exploded gun or rocket), at the moment when the
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