On the outer aspect of the myocardium is the epicardium which forms part of the pericardium, the sack that surrounds, protects, and lubricates the heart.[1] Within the myocardium there are several sheets of cardiac muscle cells or cardiomyocytes. The sheets of muscle that wrap around the left ventricle closest to the endocardium are oriented perpendicularly to those closest to the epicardium. When these sheets contract in a coordinated manner they allow the ventricle to squeeze in several direction simultaneously – longitudinally (becoming shorter from apex to base), radially (becoming narrower from side to side), and with a twisting motion (similar to wringing out a damp cloth) to squeeze the maximum amount of blood out of the heart with each heartbeat.[2]