Because the base of the heart is fixed to the mediastinum and the apex is free, the ventricle moves up and hits the anterior wall of the chest every time the ventricles contract. The location on the chest wall where the ventricle hits it is known as the apex beat. Usually, the apex beat can be located in the fifth left intercostal space, a little medial to the midclavicular line. If the heart is enlarged or if the mediastinum has been pushed to the left by fluid in the right lung or pulled to the left by collapse of the left lung, the apex beat is shifted to the left and sometimes may be felt in the left axilla.
The blood forced into the aorta during ventricular systole not only moves the blood forward in the vessel but also sets up a pressure wave that travels along the arteries. The pressure wave expands the walls of the arteries as it travels and this expansion is felt as the pulse in arteries located more superficially. Because the pulse correlates with the ventricular systole, the rate of ventricular contraction can be measured by counting the pulses felt. The regularity, rate, and force of ventriclular contraction can be evaluated by taking the pulse. For the various arterial pulsations and their locations on the surface of the body.
Normally, venous pulsation is not seen or felt, as the pressure is too low. Because there is no valve between the superior vena cava and the right atrium, abnor-mally increased pressure in the atrium may produce venous pulsations that can be seen in the neck along the jugular veins. This is known as the jugular venous pulse.
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