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Muscular Movement Conclusion

(1) The simplest muscular movement involves a coordination of muscles.


  1. The simplest muscular movement is a muscular complex.
  2. It is wrong to infer the unity of a movement as based upon the physiological unity of muscular action.
  3. With the arm in certain positions, a simple straight-line movement of the hand may necessitate movement of the entire muscular system of the arm.

(2) The smallest movement has some ''spread.''

Force of Movement

The greater the force of the movement, the greater is the spread of muscular activity. Every voluntary movement made requires some arm position.
Every arm position requires its muscular setting. We cannot speak of a definite movement without fixing both its extent and its force. A pianissimo finger-stroke through two inches has a different muscular reaction than the same finger-stroke producing a forte tone.

(3) Equal and opposite spatial movements do not necessarily mean correspondingly equal and opposite muscular movements.

  1. Raising the arm requires more energy than lowering it.
  2. Forearm supination covers a wider force range than forearm pronation.
  3. The supinators are more powerful than the pronators.
  4. Finger adduction is easier than finger abduction.
  5. The fully adducted position (fingers side by side) is the position of normal rest.
  6. The previous statements imply that equal muscular effort produced unequal forces.

(4) The size and strength of a muscule depends upon its function.

  1. The most powerful muscles of the upper limb are found in the back and chest.
  2. The next most powerful muscle is the shoulder.
  3. The next most powerful muscle is the upper-arm, forearm, and the weakest in the hand.

(5) The more extended or forceful a movement is, the more necessary is the activity of the large muscles.

  1. This is a corollary to the second conclusion on the ''spread'' of muscular activity.
  2. In an extended movement a large amplitude must be covered.
    This amplitude depends upon the movements of the large anatomical appendages (whole arm or forearm).
  3. For any movement, a certain amount of firmness must be present to permit the necessary joints to act as fixed fulcra.
  4. To maintain the fixed fulcra, large muscles will also be needed.

(6) Absence of motion does not necessarily mean absence of muscular activity.

  1. The two forces acting in opposite directions upon the same point will not produce motion at this point.
  2. Forces will nevertheless be acting at this point.
  3. Antagonistic muscular groups can act equally upon a joint.
  4. Setting the joint in a fixed position but not producing any motion at that joint is an example of two forces acting upon a point with no motion.

(7) No muscle is limited to the production of a single movement.

  1. A muscle has a primary function and always a secondary or tertiary function.
  2. Each muscle is the chief factor in a certain type of movement.
  3. As this type of movement gradually changes into other types of movement, the muscle continues to act in a continuously decreasing degree.

(8) Many movements of translation are produced by movements of rotation.

  1. The hand may move in a horizontal plane by rotation of the upper arm.
  2. The straight finger stroke may result from flexion in the hand knuckle combined with opposite extension at the interphalangeal joints.