Note:  Do not rely on this information. It is very old.


Pulse. Corresponding to each injection of blood into the arterial system, by the contraction of the left ventricle of the heart, there is a distension of the arterial tubes. This rhythmical distension can be seen in the temporal arteries of thin persons, and can be readily felt in the radial artery, which is situated quite superficially at the wrist. If one end (the short arm) of a lever be applied to the radial artery, the end of the long arm gives in exaggerated form a record of the pulsation of the vessel, and if such movement be recorded on a travelling surface what is called a sphygmographic tracing is obtained, the instrument used in making such tracing being called a sphygmograph. On such a tracing the sudden rise and more gradual fall of the pulse-wave will be depicted, and occasionally the line of ascent or descent may be broken by a notch, a common appearance being such a break near the middle of the down curve (the dicrotic notch). The chief characters of the pulse as appreciated by the fingers are its frequency, its suddenness, the tension of the artery between the pulse-beats, the fulness or smallness of the pulse, and the condition of the arterial coats. The normal pulse-rate in the adult is from 70 to 80 beats a minute. Immediately after birth the average number of pulses is from 130 to 140 a minute, and in the third year the normal rate is still nearly a hundred. The frequency of the pulse diminishes until adult life is reached, and it then undergoes still further, though more gradual, diminution with advancing years. Sometimes the characters of the pulse are almost sufficient in themselves to establish the diagnosis of certain forms of disease, as, for example, in the "water-hammer pulse" of aortic regurgitation. The study of the pulse is, moreover, a valuable guide to treatment, particularly in fevers.