Wiggle your index finger up and down. As effortless as that movement is, the mechanism enabling you to wiggle just one finger is exceedingly complex, requiring the coordinated action of nervous and muscle tissues.

Everyone who has ever thrown a ball or merely lifted a heavy object knows the great amount of power that muscles can generate. But what exactly is going on inside muscles that makes them capable of generating such force? What is the molecular engine that drives muscular contractions? Remarkably, the immense power of muscular contraction is generated through the summation of the interactions of millions of highly organized, microscopic molecules found in muscle cells.

Although the overall system is intricate, the actual molecular mechanics of muscular contraction are remarkably simple. As you explore how muscles work, keep in mind that large-scale muscular movements, such as wiggling your finger, are the result of millions of microscopic molecular interactions.