The<unk>  (lat. ictus cordis), also called the apical impulse, is the pulse felt at the point of maximum impulse (PMI), which is the point on the precordium farthest outwards (laterally) and downwards (inferiorly) from the sternum at which the cardiac impulse can be felt. The cardiac impulse is the vibration resulting from the heart rotating, moving forward, and striking against the chest wall during systole. The PMI is not the<unk>  of the heart but is on the precordium not far from it. Another theory for the occurrence of the PMI is the early systolic contraction of the longitudinal fibers of the left ventricle located on the endocardial surface of this chamber. This period of the cardiac cycle is called isovolumic contraction. Because the contraction starts near the base of the left ventricle and spreads toward the<unk>  most of the longitudinal fibers of the left ventricle have shortened before the<unk> . The rapidly increasing pressure developed by the shortening of these fibers causes the aortic valve to open and the<unk>  to move outward causing the PMI. Anatomical dissection of the musculature of the<unk>  reveals that muscle fibers are no longer longitudinal oriented but form a spiral mass of muscular tissues which may also have an effect on the ability of the<unk>  to contract longitudinally. After the longitudinal fibers contract, the ejection of blood out of the left ventricle is accomplished by the torsional (as one would wring out a face cloth) action of the circumferential muscle fibers of the left ventricle that are in the mid-portion of the ventricle and contract after the longitudinal fibers. During the longitudinal fiber contraction, the volume of the left ventricle has not changed keeping the<unk>  in intimate contact with the chest wall allowing the ability to feel the<unk>  move outward before the heart empties greater than 55% of its volume and the<unk>  falling away from the chest wall.
Apex beat
Parasternal heave
Loop mark
Isotropic bands
J wave
Spike-and-wave
Fusion beat
Stenvers projection