. A text-book of physiology : for medical students and physicians . Fig. 213.—The lever ofthe Dudgeon sphygmograph:P, The button of the spring F,to be placed upon the movement is transmittedto the lever, Fi, and thence tothe bent lever, F2, whosemovement is effected throughthe weight, g. _ The writingpoint <S, of this lever makesthe record on the smoked sur-face, A. The pulse wave obtained from the radial artery is representedin Fig. 214. It will be seen from this figure that the artery dilatesrapidly and then falls more slowly, but it must be borne in mindthat the very pointed a
. A text-book of physiology : for medical students and physicians . Fig. 213.—The lever ofthe Dudgeon sphygmograph:P, The button of the spring F,to be placed upon the movement is transmittedto the lever, Fi, and thence tothe bent lever, F2, whosemovement is effected throughthe weight, g. _ The writingpoint <S, of this lever makesthe record on the smoked sur-face, A. The pulse wave obtained from the radial artery is representedin Fig. 214. It will be seen from this figure that the artery dilatesrapidly and then falls more slowly, but it must be borne in mindthat the very pointed apex of the wave recorded by this form ofsphygmograph is due to the instrumental error referred to above,namely, the fling of the lever caused by the sudden expansion. Fig. 214.—Sphygmogram from the radial artery, Dudgeon sphygmograph: D, The dicroticwave; P, the predicrotic wave. of the artery. The ascending portion of the wave is spoken of asthe anacrotic limb, the descending, as the catacrotic limb. Underusual conditions the anacrotic limb is smooth,—that is, shows nosecondary waves,—while the catacrotic limb shows one or moresecondary waves, which are spoken of in general as the catacroticwaves. The most constant of these latter waves occurs usually THE PULSE. 525 approximately at the middle of the descent (D) and is designatedas the dicrotic wave. A less conspicuous wave between it and theapex of the pulse wave is known usually as the predicrotic wave, P,while the wave or waves following the dicrotic are designated aspostdicrotic. These catacrotic waves are too small, under normalconditions, to be felt by the. finger. Under certain abnormalconditions, however, which cause a low blood-pressure withoutmarked diminution in the heart beat, th
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