The Working Muscle

Generally stated, a working muscle is more "active" and maintains a subtle disposition of contracted fibers. The working muscle can often be discriminated by comparison to its counterpart, contralaterally. There can be noted an asymmetry and moderation of the tensile consistency; the working muscle being the more resilient or renitent in character.  It may not be a marked difference, and therefore difficult to discriminate.

A simple illustration is that of the rubber band felt through a piece of paper (though this is far from accurate).  To the novice this sensation is more accurately felt by raising the corner of the mouth in a slight smile and palpating the teeth through the working muscles and succeedingly relaxing the mouth and palpating to differentiate the non-working sensation.  The working muscle is perceptible as a portion of its fibers having definition and tissue density within its slender bands.  Again, this is often a subtle sensation and palpation practice is essential to refine the tactile senses of the student.