Black-Key Biomechanics

CMT: When we were together last time, you were talking about the natural anatomy of the fingers and biomechanics of how the pianist’s or composer’s hands lie upon the black keys. Did you know that there was an orthopedic surgery journal article about twenty years ago about “E-flat hand,” involving a pianist whose injury primarily affected the ability to play in E-flat? This was by McGregor and Glover, surgeons at the Royal Infirmary in Glasgow. The injury mainly concerned abnormally reduced flexion between the index finger and middle finger of the pianist’s right hand. They surgically divided the intertendinous connection between the extensor tendons of the two fingers on the dorsum of the right hand—the dexterity to navigate the black keys, especially in E-flat and C minor, was restored. Well, okay; great. But the notion of an injury differentially affecting performance in just one key, though—that’s just bizarre. Surely that “E-flat hand” title of the article must’ve been some sort of very bad hand-surgeon humor, don’t you imagine? Ian McGregor was a very senior consultant at that time—an editor of that journal even? He could get away with hyperbole, pulling legs a bit. They weren't serious, though!

DSM: Well, yes and no. The concept of an injury exclusively affecting playing in one key but absolutely no other keys is pretty implausible. But the notion of some gradation—some disparity of the relative impact on performance fluency among different key signatures—that does, I think, ring true. How about wrist injuries? Have there been any reported relationships of disabilities of the wrist—to playing fluency in black-intensive key signatures? The way the hands advance in black keys toward the fall-board might be expected to give rise to some susceptibility to wrist-injury-related differences, don’t you imagine? Generally, the wrist should be about on a level with the second joint of the middle finger, when the fingers are properly rounded. The knuckles will then be a little elevated. In fact, they’ll naturally take care of themselves, all things considered. But this changes subtly when you’re on the black keys a lot.

CMT: No—I’m unable to find any papers that’ve been published on wrist lesions’ effect on the ability to play in different key signatures as such. Hand surgery has only a limited role in alleviating pianists' difficulties. Apart from deQuervain’s and nerve-entrapment syndromes, there are few indications for hand surgery. Stabilizing a metacarpophalangeal thumb joint is pretty successful—there are a number of orthopedics hand surgeons doing this in pianists’ hands. Also, performing arthrodesis in painful and unstable distal interphalangeal (DIP) joints is routinely done with good results. The indications for orthopedic surgical procedures on the trapeziometacarpal joint are more controversial—the decision requires more cautious evaluation, the procedure is by no means ‘routine’, and the results aren’t currently as reliably or predictably good. Of course, wrist fractures and rheumatoid arthritis and carpal tunnel and focal dystonia and Linburg-Comstock syndrome and other things do have a big impact on playing overall. But I’ve been unable to find any studies of wrist anatomy or abnormalities differentially affecting fluency in particular keys. Oh, we continually have to work on equal finger development, Czerny-style. As you say, we can never make all our fingers equal—we’ll never make our fourth finger as strong as our thumb no matter what exercises we do. Instead, we learn to so compensate the weight and pressure of each finger so that all can produce serviceably uniform, nearly equivalent sounds. So, injury-type natural experiments aside, are there exercises involving the wrist that inadvertently produce differential effects regarding fluency in different keys?

DSM: Chopin’s étude in sixths is a good example, I think. This study needs a quiet, limpid touch—gliding rather than forceful motion. Play it at first pianissimo—the wrist low, the knuckles a little elevated, the fingers flat. In preparation for each pair of notes raise the fingers and let them down—not with a hard touch, but with a soft one. A composition like this needs to be abstract, ethereal, not quite of this earth.

CMT: Fingers’ reaching for the notes, the passing of the hand in the air and the final gentle fall on the key—not in undue haste to get there, but with confidence of reaching the key in time. What goes up must come down. This barcarolle is not easy! There’s plenty of work in it for flexible hands: it’s a study in pianissimo playing—in power controlled, held back, restrained.

DSM: On violin and other string instruments, too, we have to beware. If there be flat keys here, you’d better fortify your fourth finger! I should stretch my first finger up—or my fourth finger down—in order to play a flatted or sharped note, and my second and third fingers should stay exactly where they usually are in first position. That avoids the problem of drifting out of tune by not coming back to the right place on the string. An irritating new habit that I’ve picked up is letting my left hand slowly drift closed so that my first finger is in the right place but my fourth finger is too close, so I’m playing flat notes all the time. Shifting into half position can cause this—when I shift back to first position my hand has closed up a bit. I’m going to have to struggle to break this bad habit.

CMT: For my piano calisthenics, I play diatonic or chromatic octave scales with four repetitions or more on each note, using the fourth finger for black keys. By the way, the biomechanics of the hand on modern keyboards—has been examined at length by Kroemer and Meinke. There are several phases of finger movement that have been identified:

• Preposition: This is the phase that controls how the note will sound. It does this by determining where over the point of sound (distance) and what energy state the tip of the finger will have before gravity is allowed to take over. Any of several movements may be seen, ranging from nothing (for pianissimo) to a visible lifting of the limb away from the keyboard before it drops (for a loud and percussive fortissimo). The muscles of pronation and supination in the forearm invariably participate in this phase, and give the tiny movement a rotary component. They are large enough to develop and direct momentum in the limb yet small enough to be capable of the fine control needed to give the striking member the exact amount of speed and force that will produce the required sound. The fingers move into position to act as a conduit for the combined downward vectors, but does so against no more resistance that the resting tension of the hand held in “neutral.”
  
• Grasp: From the time gravity is allowed to act on the limb until movement away from the key, the only active forces are those sufficient to prevent the deviation of the wrist and finger from neutral position. At this point the fingers are passive conductors of force. If more than one finger is to play, the opportunity presents itself through motions of the arm and forearm to direct relatively more of the available force into one or the other, thus giving a different tonal quality and intensity to each of the tones produced. In particular, no other increased intrinsic tension is present, such as might be seen if the next finger to play began to stretch toward its target position. If the note is to be held, the limb presses the key to the key bed by the force of gravity alone until the note is released. If it is not, then the momentum imparted to the limb by the rebound from the key bed is used to “propel” it into the next reach.
  
• Release: Defined as the point at which all downward vectors of force have disappeared from the playing finger, release should probably not be considered complete until the playing finger has reached neutral position and intrinsic (isotonic) forces are at a minimum. When possible it will use the rebound from the key bed as a force propelling the finger away from the key. The trajectory of movement away from the key will be such that this movement assists rather than opposes the next reach.

DSM: You have to somehow passively conduct the energy that’s produced by other parts of your body. First of all, the element of control resides in that period of time just before gravity is allowed to act, the preposition portion of the cycle. Gravity has to carry the mass of the forelimb through the point of sound if it is to be utilized as a force. Any attempt to control the sound after the preposition phase interferes with this. Because the movements associated with preposition are so small, little is known about them.

CMT: Also, the shorter the cycle (keystrokes in quick succession), especially when the passage is loud, the more the player’s forced to utilize extrinsic forces to maintain a level of kinetic energy in his or her upper limbs. This way, passages that seem to defy the limits of human physiology are within reach.

DSM: Wristen’s recent papers have looked at specific matches of the player’s hands to the keys. Small-handed pianists preferred a smaller 7/8-size keyboard. The maximum angle of hand-span while playing a difficult piece was about 5° smaller radially and 10° smaller ulnarly for the 7/8 keyboard compared to the full-size keyboard. That led to perceived greater ease and better performance as rated by the pianists who were studied.

CMT: Look also at Miyazaki’s experiments, where he asked his subjects to identify tones by pressing the corresponding key on a piano-like keyboard—on which the black keys are smaller and further away from the subject. Could it be, they wondered, that people identified black keys more slowly because the black keys are biomechanically harder to reach? They conducted an experiment where all the buttons were geometrically equally easy for the fingers to reach. But they discovered that white keys were nonetheless identified more quickly and with fewer errors than the black ones. So there’s more going on here besides the geometry of the keyboard design—there’s also visual perception and neuropsychology of black vs white recognition.

DSM: There’s also the muscle memory—routinized associations of digits positions on keys. The thumb always stays on the white keys, never on black keys. The fourth finger always plays a black key when there is a black key to be played in the scale. The fifth finger is only used at a starting place, a stopping place, or a turning-around place. These are rules that brook not very many exceptions. And Miyazaki didn’t do the full inverse experiment with the black and white in reversed configuration.

CMT: Yes, all of these factors interact with each other. We learn to be aware of the physical activity and sensual nature of touching the keyboard in a wide variety of ways. We attend to the way a finger moves from white key to black key in the production of a melodic phrase. Awareness is also given to the way the hand must stretch, contract and shape itself to a particular melodic pattern. In this fashion, the body learns how to measure musical time in a tangible way thereby creating an exact correlation between aural thought and physical response and measurement.

DSM: We were talking about flat fingers a few minutes ago. Advantages of the so-called flat-finger position (FFP) are that this position simplifies the pianist’s finger motion and lets the fingers to relax a bit. The number of muscles needed to control the finger motion is smaller than in positions where the fingers are more curled—because all you have to do is to pivot the whole finger around the knuckle. In the curled position, each finger has to uncurl with precision every time it hits a note, in order to maintain the correct finger angle with respect to the key. The motion in FFP uses only the main finger-actuating muscles needed to press the keys. In curled positions, there’s a “latency” or delay to the finger motion; it’s more difficult to begin the finger motion and control it. The easiest way to move the finger tip rapidly in fully curled positions is to move the entire hand—and that slows things down a lot—big inertia constraint.

CMT: So with the curled position you need more physiological reserve to play at the same speed as you’d need with FFP. Contrary to conventional wisdom, you can play faster with flat fingers than with the curled position because any amount of curl will entail some curl-related latency or delay. This is important when the speed produces stress when you face a difficult passage. The amount of stress is greater in the curled position, and this difference can be enough to make you hit a speed “wall”.

DSM: There are discussions in the piano literature in which it’s claimed that the lumbrical and interossei muscles are important in piano playing, but to-date there’s no research to support these claims, and it’s not known whether these muscles play a part in FFP. It is generally believed that these muscles are used mainly to control the curvature of the fingers, so that FFP uses only the muscles in the arms to move the fingers and the lumbricals simply hold the fingers in position (curled or FFP), thus simplifying the movement and allowing for greater control and speed for FFP. Thus there is uncertainty today about whether the lumbricals enable higher speed or whether they cause curl paralysis.

CMT: Although FFP is simpler, I think all beginners should learn the curled position first and not learn the flat position until it’s actually needed. I do this with my students. If beginners start with the easier FFP, they’ll never learn the curled position well. Early players who try to play fast with FFP are likely to use fixed-phase parallel-set playing—they are then prevented from getting good finger independence. This makes for inadequate control, uneven speeds—lots of problems, lots of bad habits to break. Sandor calls the FFPs “wrong positions,” but Fink recommends certain positions that are clearly FFPs. I think it’s just a question of when to introduce the student to FFP.

DSM: Interestingly, most pianists who learn on their own use mostly FFPs. Jazz pianists—many of whom took lessons at some time in their youth but have been essentially self-taught in adult life—use FFPs more than classical pianists. And because many jazz pianists have inferior technique—but get by with it because there is less technical difficulty in jazz than in classical piano—the inferior technique tends to be spuriously blamed on the [self-styled, naïve] FFP. It’s lack of instruction and lack of critical coaching, not the use of FFP!

CMT: Regardless of FFP vs curled, the fourth finger is problematic for most people. Part of this arises from the anatomy of the muscles and tendons—it’s the most awkward finger to lift. That, in turn, makes it difficult to play fast and avoid hitting wrong notes. But the problem is worse in the curled position because of the complex motion and the latency that the curling of the finger induces. In the simpler flat-finger configuration, the problem is alleviated, and the fourth finger becomes more independent and easier to lift. If you place your hand on a flat surface in the curled position and lift the fourth finger, it will go up a certain distance. If you do this with FFP, the finger tip will go up a lot more. So it’s easier to lift the fingers, especially the fourth finger, in FFP. The ease of lifting reduces the stress when playing fast. Also, when trying to play difficult passages fast using the curled position, fingers 4 and 5 sometimes curl too much, creating more stress. These problems are diminished by using FFP.

DSM: Another advantage of flat-finger is that that position increases your reach because the fingers are already extended and straight. You can see this in videos of Horowitz and Gould. For this reason, pianists with small hands tend already to use the flat position for playing wide chords, often without realizing it. However, such people can feel “guilty” about the lack of curl and try to increase the curl. In doing this, they generate stress in the hand.

CMT: Another advantage of the FFP is that the fingers are pressing the keys with the part of the fingers with more flesh than at the finger tips. There’s some controversy about which part—the finger tip vs the fleshy part—is more sensitive to touch, in terms of the number of nerve endings and the degree to which the thickness of skin, or callus, or other factors.

DSM: With flat fingers, you can play the black keys using most of the large underside areas of the fingers; this large surface area can be used to avoid missing the black keys that are easy to miss in the curled position because they are so narrow. So it’s a good idea to play the black keys with your flatter fingers and the white keys with the fingers that have more curvature in their anatomy.

CMT: When your fingers are stretched out flat, look, you can reach further back towards the fallboard. It does require a little more force to depress the keys because of less leverage stemming from the shorter distance to the key bushing. The resulting heavier key weight allows you to play softer pianissimo. So the ability to move closer to the key bushing results in the ability to increase the effective key weight. The heavier key weight allows more control and softer pianissimo.

DSM: The FFP also allows louder fortissimo, especially for the black keys. There are two reasons. First, the area of the finger available for contact is larger and there is a thicker cushion, as explained above. Therefore, you can transmit a larger force with less chance of injury or pain. Second, the increased accuracy resulting from the larger contact area helps to produce an authoritative and reproducible fortissimo. In the curled position, the probability of miss-keying narrow black keys is pretty high—especially at fortissimo.

CMT: The ability to play fortissimo more reliably is something I hadn’t thought of before. But I’d be careful when you using FFP playing fortissimo. You’re risking hyper-extending those tendons, especially for finger 5.

DSM: I think practicing FFP should begin with the B major scale. In this key, all fingers play black keys except and 5th finger and thumb. The fingering for the right hand is standard for this scale, but the left hand has to start with the fourth finger on B.

CMT: The flat finger position is a sensitive diagnostic for technical deficiencies because of the difference in mechanical leverage at the metacarpal-phalageal joint. The fingers are stretched out longer.

DSM: If you have difficulties playing flat-fingered, try some black-key parallel-set exercises. Play all five black keys with the five fingers. Play the two-note group with thumb and forefinger and the three-note group with the remaining three fingers. There is an intermediate position in which the fingers are bent down only at the knuckles. This is called the “pyramid” position because the hand and fingers form a pyramid with the knuckles at the apex. This pyramid position is good for fast passages because it combines the advantages of the curled and flat positions.

CMT: We need a broader definition of “flat finger” playing. The straight FFP is just an extreme case, and there are lots of variations of positions between the totally flat position the curled position. In addition to the pyramid position, you can bend the fingers at the first joint from the knuckle—the “spider position,” for example. Most curl-related latency comes from bending the third phalanx of the finger. This can be demonstrated by bending only the third phalanx (if you can) and then trying to move that finger fast. The FFP simplifies the brain’s motor cortex task. Because you don’t involve the flexor muscle of the third phalanx, there are 10 fewer flexor muscles to control, and these are particularly awkward and slow muscles. So flat-finger technique that minimizes dependency on them can increase your playing speed. The flat-finger position gives more control because the relaxed third phalange is like a shock absorber—there is more flesh between the bone and the key surface. Playing with a curled position is like driving a car without shock absorbers.

DSM: You may want to lower the bench in order to be able to play with the flat part of the fingers. When the bench is lowered, it usually becomes necessary to move it farther away from the piano to provide enough room for the arms and elbows to move between the keyboard and the body. I used to sit too high and too close to the piano, which is not noticeable when playing with curled fingers. So using FFPs give you a more forgiving way to optimize the bench height and location.

CMT: At the lower heights, the wrists might sometimes fall below the level of the keyboard while you’re playing. Sitting farther away from the piano also gives you more space to lean forwards in order to play fortissimo. The extra reach, the large contact area, and the added cushion under the fingers—these make legato playing easier and quite different from legato using the curled position. The FFP also makes it easier to play two notes with one finger, especially because you can play with the fingers not parallel to the keys and use a very large area under the finger to hold more than one key down.

DSM: We should talk, too, about when you need the curled position. This position is not really an intentionally curled position but a relaxed position in which there’s a natural anatomical curl to the fingers. If you have a relaxed position that’s too straight, you may need to add a slight curl in order to get an optimal curled position. In this position, all the fingers contact the keys at an angle somewhat greater than 45 degrees (the thumb might make a somewhat smaller angle). There are some movements that are necessary for playing the piano that require the curled position. Some of these are: playing certain white keys (when the other fingers are playing black keys), playing between the black keys, and for avoiding poking your fingernails into the fallboard. Especially for pianists with large hands, it’s necessary to curl fingers 2, 3, and 4 when 1 and 5 are playing the black keys in order to avoid jamming fingers 2, 3, and 4 into the fallboard. One of the biggest disadvantages of the curled position is that the extensor muscles aren’t exercised as much as with FFP. The flexor muscles are able to overpower the extensors, and this creates control problems. In FFP, the flexor muscles are relaxed and not exercised as much. In fact, the flexor tendons are stretched out, and the fingers more flexible in general—less crampy. I wonder whether the incidence of focal dystonia is less in pianists who use FFP a lot, compared to those who primarily use curled positions…

CMT: What about the pedagogical controversy—whether we should play mostly with the curled position and add the FFP whenever necessary, or vice versa, as Horowitz did? I think a legacy of clavichord and fortepiano pedagogy is being visited upon the seventh generation of concert grand players here. Liszt suggested that each movement of the finger was connected with the whole process of movement of the playing arm, and that each rhythmic and dynamic change was linked to an inner pulse. One of Liszt’s rules was that technique doesn’t depend on exercise per se, but on the technique of exercise. Chopin also mentioned the importance of integrating hand, wrist, forearm and upper arm motions for piano playing. This is part of what led to the diversity of opinions that we see today among pianists regarding correct finger action.

DSM: Think about how FFP and what that entails for the position of the hand relative to the forearm and upper arm—how these are related to bench height. It’s easier to play with flat fingers when the bench is lower. There are lots of pianists who discover that they can play better with a lower bench position. Horowitz and Gould were examples. They claimed to get better control from FFP and the lower bench. There’s no good reason to sit overly low as Gould did, though—because you can always lower the wrist to get the same effect.

Here are some resources that may be of interest:

• Performing Arts Clinic, Brigham & Women's Hospital, Harvard Medical School Dept. of Neurology, Boston
  
• Indiana Hand Center, Indianapolis
  
• American Association for Hand Surgery
  
• Pulvertaft Hand Centre, Derbyshire Royal Infirmary, Derby
  
• British Society for Surgery of the Hand
  
• Federation of European Societies for Surgery of the Hand
  
• Health Care Institute for Performing Artists at St. Luke's / Roosevelt Hospital Center, New York
  
• German Association for Music Physiology and Musicians' Medicine
  
• Hand und Instrument
  
• Arts Medicine Europe
  
• Musicians' hand surgery clinic, Baden-Baden.
  
• Performing Arts Medicine Association
  
• The Methodist Hospital, Center for Performing Arts Medicine, Houston
  
• Mayo Clinic Orthopedic Surgery
  
• Hand and Upper Extremity Center, Cleveland Clinic, Cleveland
  
• Medecine des Arts, Montauban (Toulouse)
  
• Louis Armstrong Center for Music and Medicine, New York

And here are some relevant sources worth looking at:

• Art of Piano - Great Pianists of the 20th Century. DVD. NVC Arts, 1999. [views of Horowitz's hand positions]
  
• Golden Age of Piano. DVD. Decca, 2003. [views of Gould's hand positions]
  
• Blum J. The musician's hand: aspects of music physiology and performing arts medicine. Handchir Mikrochir Plast Chir. 2000 Sep;32(5):299-310.
  
• Brandfonbrener AG. Musculoskeletal problems of instrumental musicians. Hand Clin. 2003 May;19(2):231-9
  
• Brower H. Piano Mastery, 1915. Dover, 2003.
  
• Buck-Gramcko D. The musician's hand: 2 case reports from the hand surgery clinic. Handchir Mikrochir Plast Chir. 2000 Sep;32(5):311-5.
  
• Crabb DJ. Hand injuries in professional musicians. A report of six cases. Hand. 1980 Jun;12(2):200-8.
  
• Darrow JC Jr, et al. Distal ulnar recession for disorders of the distal radioulnar joint. J Hand Surg [Am]. 1985 Jul;10(4):482-91.
  
• Ell N. Hand surgery in musicians with rheumatoid arthritis. Handchir Mikrochir Plast Chir. 2005 Feb;37(1):40-51.
  
• Engel KC, Flanders M, Soechting JF. Anticipatory and sequential motor control in piano playing. Exp Brain Res. 1997 Feb;113(2):189-99.
  
• Fink S. Mastering Piano Technique. Amadeus, 2003.
  
• Green D, et al. Operative Hand Surgery. Churchill Livingstone, 2005.
  
• Henderson P. Piano Fingering. Indiana Univ, 1994.
  
• Kelley R. Piano Fingering. Furman Univ, 2001.
  
• Kroemer KHE. Keyboards and keying: An annotated bibliography. Universal Access in Info Soc. 2001; 1(2):99-160.
  
• Larsson L-G, et al. Benefits and disadvantages of joint hypermobility among musicians. New Engl J Med 1993; 329: 1079-82.
  
• Leijnse JN. Measuring force transfers in the deep flexors of the musician's hand: theoretical analysis, clinical examples. J Biomech. 1997 Sep;30(9):873-82.
  
• Leijnse JN, et al. The hand of the musician: the kinematics of the bidigital finger system with anatomical restrictions. J Biomech. 1993 Oct;26(10):1169-79.
  
• Leijnse JN, et al. Biomechanics of the finger with anatomical restrictions--the significance for the exercising hand of the musician. J Biomech. 1992 Nov;25(11):1253-64.
  
• Markison RE, Johnson AL, Kasdan ML. Comprehensive care of musical hands. Occup Med. 1998 Jul-Sep;13(3):505-11.
  
• McGregor IA, Glover L. The E-flat hand. J Hand Surg [Am]. 1988; 13:692-3.
  
• McKee N. Challenges in Hand Surgery. Saunders, 2005.
  
• Meinke WB. The work of piano virtuosity: an ergonomic analysis. Med Prob Perf Artists 1995; 10(2):48-61.
  
• Miller G, Peck F, Brain A, Watson S. Musculotendinous anomalies in musician and nonmusician hands. Plast Reconstr Surg. 2003 Dec;112(7):1815-22
  
• Nourissat G, Chamagne P, Dumontier C. Reasons why musicians consult hand surgeons. Rev Chir Orthop Reparatrice Appar Mot. 2003 Oct;89(6):524-31.
  
• Olafsdottir H. Is the thumb a fifth finger? Exp Brain Research 2005;160:203-13.
  
• Parlitz D, Peschel T, Altenmuller E. Assessment of dynamic finger forces in pianists: effects of training and expertise. J Biomech. 1998 Nov;31(11):1063-7.
  
• Parry CB. Prevention of musicians' hand problems. Hand Clin. 2003 May;19(2):317-24
  
• Sandor G. On Piano Playing: Motion, Sound, and Expression. Schirmer, 1995.
  
• Schmidt H-M, et al. Surgical Anatomy of the Hand. Thieme, 2004.
  
• Siemon B, Borisch N. Problems of the musculoskeletal system in amateur orchestra musicians under special consideration of the hand and wrist. Handchir Mikrochir Plast Chir. 2002 Mar;34(2):89-94.
  
• Smahel Z, Klimova A. The effect of age and exercise on wrist mobility. Acta Chir Plast. 2005;47(3):92-7
  
• Smahel Z, Klimova A. The influence of age and exercise on the mobility of hand joints: 1: Metacarpophalangeal joints. Acta Chir Plast. 2004;46(3):81-8.
  
• Smahel Z, Klimova A. The influence of age and exercise on the mobility of hand joints: 2: Interphalangeal joints. Acta Chir Plast. 2004;46(4):122-6.
  
• Smahel Z, Klimova A. The influence of age and exercise on the mobility of hand joints: 3. Thumb joints. Acta Chir Plast. 2005;47(2):47-50.
  
• Warrington J. Hand therapy for the musician: instrument-focused rehabilitation. Hand Clin. 2003 May;19(2):287-301
  
• Wilson FR, Wagner C, Homberg V. Biomechanical abnormalities in musicians with occupational cramp/focal dystonia. J Hand Ther. 1993 Oct-Dec;6(4):298-307.
  
• Winspur I, Parry CBW. The Musician's Hand: A Clinical Guide. Dunitz, 1998.
  
• Winspur I. Special operative considerations in musicians. Hand Clin. 2003 May;19(2):247-58.
  
• Winspur I. Advances in objective assessment of hand function and outcome assessment of the musician's hand. Hand Clin. 2003 Aug;19(3):483-93.
  
• Winspur I, Parry CBW. Musicians’ hands: A surgeon’s perspective. Med Prob Perf Artists 2000;15(1):31-40.
  
• Wristen BG, et al. Assessment of muscle activity and joint angles in small-handed pianists. Med Prob Perf Artists 2006; 21(1):3-11.
  
• Yu H-L, et al. Atlas of Hand Anatomy and Clinical Implications. Mosby, 2003.
  
• Feldenkrais Method. Indiana Univ.
  
• Allen MR. U.S. Patent 4,480,519 Musical Instrument with improved keyboard. 06-NOV-1984. An improved keyboard for a musical instrument includes a plurality of keys arranged in a side-by-side order, all lying in a common plane. Different embodiments of the invention have a varying number of keys per octave, from as small as 12 keys per octave to as high as 90-120 keys per octave!?!