[Agonist-antagonist mechanics of the descendent and ascendent segments of the ventricular myocardial band].

In this article the macroscopic structure of the ventricular myocardium is described, which is configurated as a band along which four segments can be distinguished. Such band traces a helicoids with two spiral turns in the space, in its trajectory from the pulmonary artery root to the aortic root, delimits both ventricular cavities. Our interest in achieving the knowledge of the coherent relationship between that anatomical fact and cardiac mechanics, which necessarily exist between the form and the function of any organ, has led us to perform some experimental approaches which show that the volume decrease of the ventricular cavities takes place, simultaneously with the descent of the base, thanks to the agonist contraction of the descending segment of the band, previously stretched out in a rectilinear way. Meanwhile, the volume increase takes place, simultaneously with the ascent of the base, as a consequence of the antagonist contraction of the ascendent segment of the band, previously extended in a curvilinear way.