The framework of the arm and hand consists of thirty bones: 1 for the upper arm, 2 for the forearm, 8 for the wrist, 5 for the palm of the hand, and 14 for the fingers and thumb. The hand and wrist are, strictly speaking, attached to only one of the two bones of the forearm.



This may easily be proved. Let the right arm be loosely extended, and the hand made to-turn half round and back again without bending at the wrist, the fingers of the left hand during this motion touching lightly the " under" bone of the right arm close to the elbow. As the hand turns, the upper bone alone turns with it, attached to, and "rolling" on the lower one at both elbow and wrist.

The terms "under" and "upper" are applied only relatively to the two bones of the forearm, as by means of motion at the shoulder-joint their respective positions may be reversed. In the present instance the position in which they are regarded as " upper " and "under" is that in which, when the arm is outstretched, the thumb is uppermost.

The bones of arm and hand are dependent for there motion on the action of the muscles, which are attached in the case of the hand and arm nearly always to bone, for the purpose of moving it. A bone cannot be altered in position unless the muscle or muscles moving it are altered in shape. When uncontracted, every muscle assumes the greatest length and the softest consistency natural to it. When forcibly contracted it is shortest and hardest.

There are two sets of muscles used to move the hand, the flexors and the extensors. The former are situated chiefly on the front of the forearm, and draw the fingertips towards the palm of the hand; the latter, situated on the back of the arm, are instrumental in opening the hand and straightening the fingers. The contraction of either set of muscles draws the bones into which they are inserted towards the bone from which they originate.

If the hand and arm were allowed to fall loosely by the side, and if the attitude assumed by the fingers were noticed, it will be seen that they do not hang straight, but are kept partially bent or flexed. If they are then straightened or extended, the stretch can be felt, and concentration is needed to keep this position, and when this effort is relaxed, the fingers return to their previous rounded shape.

The muscles when lying at rest, or in other words, without contraction of either flexors or extensors, cause this attitude of the fingers. It is to be noticed that this natural attitude is the same as that used in playing on the piano.

It may be as well to employ in future the words "stiff" and "loose" to denote the two states of the muscles: the former to the forcibly contracted, the latter to the perfectly natural state.

Of more practical use to the piano student than knowledge of how muscles contract is the knowledge of what causes muscles to contract; Once a piano student understands the causes of muscle action, then the student will learn to play with expression and develop technique.

It will be sufficient to indicate here, very briefly, what the non-medical student may learn fully and clearly from such works as, say, Professor Huxley's "Lessons in Elementary Physiology." The brain is the organ from which originate the impulses which cause the body to act upon external objects.

These impulses are sent to the muscles through channels called nerves. Commands from the brain are sent out through one set of nerves, and impressions which the brain receives from outside are brought in through another set.