This is generally the best way to use the fingers when speed, precision and independence are a priority. I have exaggerated the movement a little to make it clear.
Note that the finger flexes from the first knuckle (MCP joint) and extends at the middle one (PIP joint). There should be no active straightening out of the finger, but rather a feeling of allowing it to unbend naturally — like the way your knee unbends when you put your foot down.
Video No 2: Flexing movement using the intrinsic muscles
See above. The fingers are lifted by the General Extensor — a large extrinsic muscle in the forearm — which, on its own, cannot straighten the fingers completely as the intrinsic muscles are needed to complete the movement. Because the General Extensor can extend only the 1st phalange completely, the other two phalanges are flexed passivley by the natural tonus of the extrinsic flexing musicles (FDP and FDS).
The fingers are then flexed by the intrinsic muscles (the interossei and lumbricals) which have attachments to the bases of the first phalanges (flexing at the MCP joint) and which also send tendons to the dorsal side of the fingers, where they join the extensor expansion, thereby causing the other two joints to extend.
Note that the FDP Muscle is often used as a limiter, setting the limit of finger extension so that the finger tips follow a prescribed path. This is not the same as using the FDP actively.
Note also that one frequently allows the fingers to be lifted by the keys, rather than using the General Extensor to raise them. This can reduce fatigue considerably.
Video No 3:Finger touch
Showing the use of the intrinsic muscles of the hand (interossei and lumbricals). It can be seen that the fingers flex from the first knuckle (MCP joint) and extend at the middle knuckle (PIP joint)
There are many advantages in this coordination: The intrinsic muscles allow the fingers to work independently of each other, the movement adapts to the movement of the key - avoiding friction, the muscles are fast and close to the fingers, they are extremely sensitive (through proprioceptive feedback) to the weight and movement of the key.
For a more detailed explanation see Curved Fingers — and Tension?
You will notice that there are small adjusting movements of the whole arm and hand accompanying each finger movement. These are not planned, but are the result of the whole arm and hand working together as one mechanism. Lack of this continuous awareness and support is one of the most noticeable characteristics in less experienced players.
Video No 4: Actively using the Flexor Digitorum Profundus Muscle
This is typical of the ‘claw like’ touch which is produced when pianists are overly concerned about “keeping their finger tips firm.”
It activates the deep finger flexor in the forearm (flexor digitorum profundus muscle) which tends to bind all the fingers together. It is useful for heavy duty work such as carrying suitcases and hanging from branches, but inhibits independence of the fingers in piano playing.
It is nevertheless helpful in heavy octave and chord work, where the hand can be used as a unit. Note that the finger tips flex slightly during the stroke and that there is a certain amount of friction against the key. This touch is responsible for much of the stiffness in the hand and wrist that is to be found amongst piano students.
Video No 5: Using the Flexor Digitorum Superficialis Muscle — articulating the fingers from the middle (DIP) joint
This is an example of the ‘collapsing finger tips’ that some teachers become worried about. It is often a result of the pupil trying to keep firm finger tips but instinctively bypassing the problematic FDP by using the FDS instead, resulting in the flexing of the PIP joint (see note for Video No 1). The FDS is another of the big flexors in the forearm and is attached to the middle phalange of the fingers, close to the PIP joint.
The best way to avoid the collapsing finger tip problem is to use the intrinsic touch as described above, thereby extending the PIP joint and not pulling the finger tip joint (DIP joint) in.
The FDS has its uses, however. It can be used for positioning the fingers on white notes (as in the the B Flat Minor and B Minor scales) without activating the FDP and stiffening the hand. It can also be used for repetition touch, where the fingers are drawn into the palm in quick succession (if the FDP is used the hand can become very stiff). This kind of repetition touch can, however become very tiring, and should be used only for special effects.
Video No 6: Arpeggio
Showing an upwards arpeggio of C in the right hand. Notice the way the thumb ‘falls’ off the keyboard as the second finger plays and travels in a comfortable semicircle to the next C. This is very helpful for players with large hands and avoids a cramped thumb position. It is also a natural movement of the 1st metacarpal (1st thumb bone) from its saddle shaped joint.
The forearm rotates slightly (pronation) to help the thumb pass under the hand — significantly increasing its reach. It is not commonly understood that the thumb also pronates as it passes under the hand and that it should therefore play on the nail. Attempting to make it play in the same position as when it is beside the hand is a common fault, causing the forearm to supinate, the fingers to play at a weak angle, and drastically
shortening the reach of the thumb. This usually results in an excessive lateral deviation of the wrist in order to compensate.
The arm rotates the hand over the thumb (supination), saving time by preserving the hand/thumb relationship and the rest of the hand position.
Pronation begins again as the second finger plays.
Video No 7: Arm touch
The opening of the Schumann Piano Concerto shows what I describe as "arm touch." The stroke is basically from the elbow, and the wrist is used in a flexible way to allow the hand to remain near the keys. The wrist should relax as much as possible in the microsecond after the stroke and firm up as the chord is sounded - the timing is critical. The fall of the wrist, and the elbow remaing at a fixed distance from the keyboard, ensures that the hand is
pushed towards the keys, which is a mechanically sound way of playing them with maximum strength and minimum fatigue. Note the placing of the hand when moving from black to white keys. The adjustment is made from the shoulder, very quickly, and the hand always pushed forward into the keys - however slightly - by the falling wrist, and never dragged back as it plays. This is hard to see because the upper arm movement is so quick and the wrist movement often quite small, which is why I have included
slow and faster close-ups of the first few chords.
7a: No 7 slowed down and close-up 7b: Faster close-up
*With apologies to the splendid film of the same name