VIBRATION OF THE BODY DUE TO ACTION OF THE HEART. 157 



When the legs are crossed, the pulse-beat and the recoil-elevation are dis- 

 tinctly recognized in the supported limb. 



If with the body at rest in the recumbent position the lower and upper incisors 

 are brought gently in contact and kept so, a double beat of the teeth against each 

 other will become audible, as the pulse-wave in the facial arteries elevates the 

 lower jaw. The rapidly succeeding second impact is not due to the recoil- 

 elevation, however, but to the concussion produced by the closure of the semilunar 

 valves. 



A pulsatory movement is communicated to the brain by the large arteries 

 at its base and in which all the individual features of sphygmographic tracings 

 made from the cerebral arteries are recognized. 



Among the pathological phenomena of the arterial pulse must be mentioned 

 the systolic pulsations in the epigastrium, which are produced in part by the 

 heart in cases of hypertrophy of the right or left ventricle when the diaphragm 

 is depressed, and in part by the forcible pulsation of the abdominal aorta or of 

 the celiac axis, which is usually dilated under such conditions. Abnormal dilata- 

 tions (aneurysms) of the arteries also occasion abnormally strong pulsations in 

 other situations, as, for example, in the trachea in cases of aneurysm of the ascend- 

 ing or transverse position of the aorta. 



Hypertrophy and dilatation of the left ventricle may cause marked pulsation 

 in the arteries lying nearest the heart. In the presence of similar conditions in- 

 volving the right ventricle the pulsation of the pulmonary artery in the second 

 left intercostal space is intensified and becomes both visible and palpable (Fig. 34). 

 In cases of aortic insufficiency with good compensation in vigorous individuals 

 when the spleen is swollen and palpable (acute infection), this organ also pulsates. 

 Pulsation is visible also in the penis. In cases of exophthalmic goiter the spleen 

 may pulsate for months. 



VIBRATION OF THE BODY DUE TO THE ACTION OF THE 

 HEART AND THE COURSE OF THE BLOOD-WAVES. 



The movement of the heart and of the pulse communicates a vibration to 

 the body as a whole. When a person stands erect on the platform of a spring- 

 scales, the pointer instead of assuming a position of rest plays up and down in 

 accordance with the phases of the heart's action. 



In his observations (Fig. 63, I) Landois employed a low box open at the 

 top (K), with a number of rubber bands, close together, stretched across, not far 

 from one of the narrow sides at a b. A quadrangular board (B) was then placed 

 with one extremity resting on the rubber bands and the other on the narrow edge 

 of the box. The subject to be experimented with (A) takes his position on this 

 board and stands erect and steady. 



In order to determine the cause of the individual indentations in the curve, 

 the vibration-curve and the curve of the apex-beat were recorded at the same 

 time for the same individual. For this purpose one box (p) of Brondgeest's pan- 

 sphygmograph (Fig. 44) is applied to the vibrating board, and the pad of the 

 other box to the situation of the apex-beat in the person to be examined. Both 

 writing-levers record their curves on the plate attached to the vibrating tuning- 

 fork: the upper is the vibration-curve, the lower the curve of the apex-beat. 



As it is impossible to exclude the marked vibrations in the apparatus itself, 

 the information obtained with regard to the mode of production of the vibrations 

 is only approximately accurate. At the instant of ventricular systole there occurs 

 a short depression, corresponding to the greater pressure of the body on the 

 elastic support ; then the body rises suddenly in response to the upward impulse 

 of the blood- wave in the carotid and subclavian arteries. After the closure of 

 the semilunar valves, which is registered by a slight elevation, the blood-wave, 

 as it courses down the body again, causes increased pressure on the platform. 

 The upward movement that now follows may be due to the centripetal wave that 

 precedes the dicrotic wave. The number of inertia-oscillations of the vibrating 

 base that take place until the next heart-beat will depend on the duration of 

 the individual heart-beats. 



Pathological. In cases of insufficiency of the aortic valves the vibration com- 

 municated to the body by the action of the heart is marked (Fig. 63, III). The 

 highest apex of the curvet as well as the characteristic drop immediately preceding 

 the ascending limb, corresponds to the ventricular systole. Below the apex of the 



