Piano Technique 2

  1. The Flexor Digitorium System
  2. The Interossei
  3. The aim of good Practice
  4. Fundamental Guidelines

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KT 2.1 - The Flexor Digitorium System

Finger movements are largely controlled by two muscle systems.
The first system, the Flexor Digitorium system, is located in the upper part of the forearm near the elbow. These muscles extend with long tendons that run along the forearm, under the wrist all the way to the knuckles and finger joints.

This muscle system enables us to have a firm hand grip, strong enough to carry a suitcase, or even hold our entire body weight when hanging from a horizontal bar (or tree branch).

This Flexor Digitorium system consists of :

  • the Flexors Digitorium Profundus, which run from the elbow, under the wrist, to the 1st finger joint (nearest the finger tip) of each finger.

  • the Lumbricals, branch off from the Flexors Digitorium Profundus at a point within the hand palm and run to each knuckle joint.



Above muscles are used to curve (and close) the fingers of the hand.

To do this however another set of muscles (the Flexor & Extensor Carpi) must hold the wrist firm (therefore stiffen the wrist), otherwise the Flexor Digitorium muscles would roll up the fingers, hand and wrist like a bamboo curtain.

(The Extensors Digitorium muscles (not shown in above diagram) are used to straighten the finger and knuckle joints, opening the hand. These muscles and their tendons run from the elbow, over the wrist and the back of the hand to connect with the knuckle and finger joints via the Extensor Expansion sheet, that extends over the back of each finger.
More about this muscle system below.)

The Flexor Digitorium muscle system is very powerful and we use it continuously for most of our finger movements.
However these muscles are not suitable for a good piano technique, because :

  1. the muscles are located largely outside the hand, too far away from the required delicate finger action.

  2. they require a degree of stiffening of the wrist.

  3. the key stroke becomes a pushing action, rather than a freely rebounding gravity stroke.
    This results in a lack of tone quality, resonance, clarity and fluency .

  4. excessive use of these muscles in piano playing can easily lead to repetitive strain injury (rsi) and inflammation of the wrist (with its carpal canal).

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KT 2.2 - The Interossei

The second muscle system controling finger movement is located entirely within the hand.
It consists of the Palmar and Dorsal Interossei muscles. These are grafted on either side of the metacarpal bone (palm bone) for each of the four fingers and run to the finger bone (phalange) just past each knuckle.


Used individually the Palmar interosseus pulls the finger sideways in one direction, the Dorsal interosseus sideways in the opposite direction.


When used simultaneously the Palmar and Dorsal Interossei flex the knuckle joint.
Most importantly these muscles are located entirely within the hand palm, and therefore can flex the knuckle joint (and achieve a proper finger action) without stiffening the wrist.

For a good finger action in piano playing we must therefore use the Interossei muscles and flex the fingers from the knuckle joints. This leaves the wrists relaxed and flexible.

There is however a problem .
In every day finger movement the Interossei play only a secondary and supportive role in flexing the knuckles.
The prime movers in knuckle flexion are the Lumbricals, for two reasons :

  1. When the knuckle joint is fully extended the Interossei are parallel to, and in line with the palm and finger bone.

    In this position the Interossei cannot start to flex the knuckle joint.

    The Lumbricals approach the finger bone at a larger angle than the Interossei.
    This means that they can flex the knuckle joint even when the knuckle joint is fully extended.


    The Lumbricals are therefore the starter muscles for the knuckle flex action.

  2. The Lumbricals, being an offshoots of the powerful Flexors Digitorium Profundus are much stronger than the Interossei muscles.
We therefore rely on the Lumbricals to do most of the knuckle movements throughout our daily activities, including our finger actions on ther keyboard.

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KT 2.3 - The aim of good Piano Practice

It now becomes clear that in order to develop a good finger technique on the piano it is necessary to reverse nature.

You must upgrade the Interossei from weak supporting muscles to become the Prime movers and learn to trust and rely on them in that dominant function.

As this starts to happen the role of the Flexors Digitorium and Lumbricals will gradually diminish to a secondary function involved mainly when special play techniques require this.

To develop the Interossei muscles you must :

  1. Always play with a good hand position.
    The knuckle joint is not straight but slightly flexed.

    In this position the Interossei can function as starter muscles.

  2. Develop Interossei muscle strength.
    Through regular technique practice as outlined in this Course consisting of
    1. warm ups
    2. fixed hand position (FHP) exercises
    3. accented scales & arpeggios
    4. technical pieces
Gradually the Interossei will become strong enough to support the hand and arm on their own. As you start to trust their strength, Flexor and Lumbrical support phases out.

This will then free up the wrist, enabling the development of tone, resonance, clarity and fluency in your playing.

Just playing piano regularly does not necessarily strengthen the Interossei muscles.
But sustained regular practice of the correct exercises will.

Gradually you will start to feel a peculiar sensation within the palms of your hands. This a sign that the Interossei are growing, becoming more powerful, expanding the width of the hand.

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KT 2.4 - Fundamental Guidelines

Good piano technique maximises the use of two sets of muscles.

  1. The Interossei, to support the weight of the hand, arm or body and to assist when required to the gravity keystroke.

  2. the Extensors Digitorium, to lift the fingers off the keyboard after they have played each note.
    (Extensor Digitorium actions do not stiffen the wrist, as the natural weight of the hand prevents any upwards flexing or instability of the wrist.)

For a good finger technique follow these simple guidelines :

  1. Keep the hands always over the keyboard (not in front of it) with the thumbs pointing downwards, so that the weight of the hand is supported by the fingers (Interossei).

  2. Keep the hands balanced on the fingers, with a slight pressure forward toward the piano. (This keeps the finger joints locked in position.)

    Never pull the hand backwards, for this either causes the fingers to collapse, or, in an attempt to prevent this, will bring the Flexor Digitorium muscles into action causing stiffening of the wrist.

  3. Use the knuckle joints for all finger action.

  4. Use gravity, viz. the natural drop of the finger, hand or arm, as the main source of energy.

It is most useful to have some understanding of the the muscle actions for a good finger technique.
However do not become obsessive about it while practising.
Just follow the simple instructions provided in this Course and things will fall into place naturally.

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© 1999 Michael Furstner (Jazclass)