1 When fixing the wrist in dorsi-flexion to assist flexion of the fingers, the dorsi-flexors of the wrist are regarded by Wood-Jones as "fixation muscles."

The seventh principle that we have to recognise is that, though a muscle may have the potential power of contracting throughout a certain range of movement, it may not have the strength as yet for the sustained effort involved. Under these circumstances it should be taught to contract and perform the first portion of the movement. A short rest follows, supporting the limb in its new position, if necessary, so as to allow complete rest. After a few moments the next portion of the movement can be performed, and so on until the full movement has been accomplished. A method of training a muscle towards sustained effort has been indicated when dealing with assistive movement. (See pp. 94 to 101.)

The eighth principle is well known and recognised, viz., that no enfeebled muscle must ever be stretched. This is recognised indeed when certain muscles, e.g., the long forearm extensors, anterior tibial group or deltoid, are paralysed: it is astounding how widely it is neglected in many other instances. Beyond all question the most important single muscle in the upper limb is the opponens pollicis, and yet it is rare to find this placed in the "rest position" when paralysed. The neglect to apply splintage to all cases of ulnar paralysis has also been responsible for much evil. The question of splintage is considered later. (See Chapter XXXII (The Combination Of Massage And Splintage In Orthopaedic Surgery).) The interpretation put on this eighth principle is, most unhappily, varied. Some hold that a weak muscle must be kept uniformly in a condition of complete relaxation until it can perform its function. This is irrational, for a muscle mass consists of more than contractile tissue: much of it is merely elastic, namely, all the fibrous tissue in the mass. Deprive this of its physical property of shortening and lengthening, and it will undergo a process already spoken of as adaptive shortening. Then, when recovery has taken place, function is well-nigh impossible. Moreover, we have other things upon which movement, and particularly co-ordinated movement, is dependent. The ligaments of joints and all tendons possess elastic properties. Unvaried relaxation leads to adaptive shortening in these, and function is further impeded. It is useless to have a perfect muscle wherewith to move a joint if the joint has been fixed by shortened ligaments on one side, and possibly is even partially dislocated by undue stretching of the ligaments on the opposite side. The elastic property of muscle, tendon and ligament throughout the limb must be maintained, and this is effected by relaxed movement. Further, co-ordination of movement is largely a question of joint-sense, and this must be maintained intact as far as possible from the outset. Relaxed movement, through at least the inner half of the range of movement, should therefore be a daily task to be conscientiously performed. Full movement should be withheld until recovery is well advanced.

The ninth principle is always to be willing to own up to having attempted too much. If on any day the power of contraction, or the amount of movement performed is less than that of the previous day, massage and relaxed movement alone should be given, and all voluntary effort is postponed to the following day. If we never do or prescribe too much, we may be sure we are not doing enough.

The tenth principle is that we must be sure that we properly instruct our patients in regard to the posture to be assumed between the times appointed for definite activity. These will be indicated as we consider the training of each muscle group.

The eleventh principle is one that requires emphasis, as it is contrary to the teaching of certain schools of thought. When a muscle is weak, there is no need to check all action in the antagonist for fear that it should over-develop its strength. This is a theoretical argument and expresses fear of a danger which, in practice, has proved to be a mere phantasm. The only thing that is necessary is so to limit its activity that the weakened muscle is not stretched. In fact, we have seen that one of the functions of a muscle is, so to speak, voluntarily "to pay out the slack" by gradual stages as its antagonist contracts. Let us from the outset, then, cultivate and re-educate this important function in the antagonist. Otherwise we are failing in our task of re-educating co-ordination. This leads us directly to: -

The twelfth, and last, principle. Nature has decreed that recovery in any shape or form requires efficient blood supply.

Cut off activity from a limb in which a muscle is paralysed and we do all we can (short of applying a tourniquet) to cut off the blood supply, and this means depriving the paralysed muscle of its much-needed nutriment. Let us encourage, therefore, the fullest possible activity in all the uninjured muscles in the limb, taking only the one precaution, namely, to prevent stretching of the enfeebled muscle. Thus we can maintain or improve circulation, and the joint and muscle senses throughout the limb, and maintain health, nutrition and co-ordination - and all this in readiness against the day of recovery in the weak muscle. Surely this is rational treatment, and better than leaving a limb to waste and shrivel and to lose all sense of movement and co-ordination. Then when the muscle has once more power to act, so poor is coordination and control over the rest of the limb that training may be well-nigh impossible. In addition, both the nerve-paths which convey sensation, and those over which travel the impulses compelling voluntary movement, are capable only of poor conductivity. Disuse atrophy is as hard, and often harder, to cure than atrophy due to injury; and often, indeed, imposes a greater disability than the original lesion. Let us, therefore, give our weakened muscle the best chance it can get of rapid recovery, and let its first tentative attempts at contraction be performed in a limb that is as nearly perfect as it is in our power to keep it. Let it also find, on its re-awakening into activity, every sense as unimpaired as possible and an adequate blood supply upon which to draw for its re-development.