Archives of internal medicine . the deep cardiac dulness and assuch have a distinct value as a check on the examiners technic Butbecause they are always measured in the horizontal direction withoutr^eference^to the obliquity of the long axis of the heart, their numerical * From the Department of Internal Medicine, University of Michigan. 138 THE ARCHIVES OF INTERNAL MEDICINE value depends directly on the angle of obliquity, approaching the longdiameter with a transverse position, and the transverse diameter with avertical position of that organ. The sum of the two, therefore, bears nofixed rel
Archives of internal medicine . the deep cardiac dulness and assuch have a distinct value as a check on the examiners technic Butbecause they are always measured in the horizontal direction withoutr^eference^to the obliquity of the long axis of the heart, their numerical * From the Department of Internal Medicine, University of Michigan. 138 THE ARCHIVES OF INTERNAL MEDICINE value depends directly on the angle of obliquity, approaching the longdiameter with a transverse position, and the transverse diameter with avertical position of that organ. The sum of the two, therefore, bears nofixed relation to the size of the heart and any conclusions drawn from acomparison of such values must be inaccurate. The transverse diameteris also an inaccurate criterion, because its right lower extremity is not afixed point, but depends on the position of the heart with reference tothe diaphragm. The orthodiagram of the heart is never a closed figure (Fig. 3). Theoutline cannot be followed through the shadows of the sternum and the. Fig. 1.—Normal orthodiagram showing usual dimensions vertebral column above, or that of the liver below. Before the area canbe determined the figure must be completed. This is usually done infree-hand, in broad curves to suit the notions of the observer. The upperborder usually shows only a short defect and the probable position of theline bridging it is fairly well defined. The lower border is often sodeeply sunk in the liver shadow that it is absurd to attempt to supply normal hearts this lower border is a fairly straight line, but pathologic-ally it may become considerably curved. Therefore the completed heartoutline represents only the examiners opinion of its size and shape. /. G. VAN ZWALUWENBERG—L. F. WARREN 139 The estimation of the area so enclosed is best accomplished by the useof the planimeter, an instrument used by engineers for measuring irregu-lar^ areas. Its scientific accuracy is limited only by the exactness withwhich the circ
Size: 1548px × 1614px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidarchi, booksubjectmedicine
