THE HEART AND AORTA
The study of the normal heart action is attracting an increasing amount of interest. Keith1 calls attention to the fact that the heart functionally consists of a central pump, the left ventricle, with three subsidiary loading pumps, the right and left auricles, and the right ventricle. Each chamber has a fulcrum, that of the auricle being applied through the fixation to the dorsal pericardial walls and through the pericardial extensions on the pulmonary vessels and lungs to the costal and diaphragmatic chest wall; the ventricles have two fulcrums, the fixed ascending stem of the aorta, and the movable fulcrum at the apex.With ventricular contraction the auricular base about the mitral and the tricuspid rings is reduced in size and through the action of muscles acting from the apical fulcrum is drawn down toward the apex, enlarging the auricles. This is the key to the
CALHOUN H. RÉSUMÉ ON THE CIRCULATORY SYSTEMREVIEW OF LITERATURE OF 1917, 1918 AND 1919. Am J Dis Child. 1920;19(1):62–85. doi:10.1001/archpedi.1920.01910190070006
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