Stiffness

“ Stiffness, also, has a decided effect upon the carriage of the body. One who has always worn stiff, clumsy foot-gear has a stiff, awkward walk, because all the muscles of the foot and leg brought into play by natural walking have been interfered with and cramped by the miserable clogs on the feet. As these will bend, or allow the foot to bend, but very little, there can be but little use of the muscles which form the calf of the leg and raise the heel. ”

“ Stiffness is a variable feature--in some cases amounting to absolute rigidity, so that no ordinary force will elicit movement. It is characteristic of this, as of other neuroses, that the symptoms come and go without sufficient cause. When the patient's attention is diverted, the pain and stiffness may disappear. There is no actual swelling of the joint, although there may be an appearance of this from wasting of the muscles above and below. If the joint is kept rigid for long periods, secondary contracture may occur--in the knee with flexion, in the hip with flexion and adduction. ”

“ A feeling of unpleasant stiffness may be complained of on his assuming this manly attitude, and this arises from the muscles of the chest and back being brought more into action, and also to the back part of the intervertebral cartilages having become thickened, from his long habit of stooping. ”

“ As an illustration of this analysis of muscular stiffness let us consider the actions of writing, when performed under the conditions just described. It is possible to write with the hand and arm in a state of muscular stiffness. But one does not write so easily, so rapidly, nor so well with the arm stiff as with the arm normally relaxed. Closer attention must be paid to the forming of the letters, and more effort must be put forth to write with the muscles stiffened ”

“ Muscular stiffness increases the difficulty of complex movements. Not only is unnecessary strength exerted; the stiffness of the joints also interferes with the freedom and facility of motion. But this unfavorable condition does not [Pg 243] upset the power of coördination. The instinctive connection between the nerve centers of consciousness and the motor centers is not broken. Although hampered in their efforts, the muscles are still able to execute the demands of consciousness. ”

“ The hand stiffens in consequence of the close attention paid to its movements. This stiffness will extend to the arm, and even to the shoulder, if the exercise be continued long enough and with sufficient intensity of attention to the hand. ”

“ In other words if a man stands up only straight in an abstract way, letting his hands fall glued to his side with no interval of separation, his legs in the same way being close to each other, we receive an untoward expression of stiffness, even although in the first instance this is due to no compulsion. ”

“ Nature is first enormously wise and then a little blind. In another example I can bring this out a little better. You have sprained your knee and the knee gets very stiff. That in itself is good; it is a defencive reaction. The stiffness is like a splint. The knee ought to be kept quiet. So far so good. But nature overdoes the thing. ”

“ In two or three weeks we shall work the stiffness out of her joints and have her performing as smoothly and softly as human muscles, and then we shall speak out the big secret and let the world come and gaze. ”

“ But I say, the parts that are rotten give elasticity to those that are sound: they give them elasticity, elasticity, elasticity. If it were all sound, it would break by its own obstinate stiffness: the soundness is checked by the rottenness, and the stiffness is balanced by the elasticity. ”

“ The effect of the pressures applied to a piece, consisting of the load and the supporting resistances, is to force the piece into a state of strain or disfigurement, which increases until the elasticity, or resistance to strain, of the material causes it to exert a stress, or effort to recover its figure, equal and opposite to the system of applied pressures. The condition of stiffness is that the strain or disfigurement shall not be greater than is consistent with the purposes of the structure ”

“ When a cord is used to transmit a force from one direction to another, its stiffness renders some force necessary in bending it over the angle P, which the two directions form; and if the angle be sharp, the exertion of such a force may be attended with the rupture of the cord. ”

“ It would not do, for the force of its stiffness would be relaxed by its being continually bent, and it would be lessened and destroyed, and when the time came for it to send stouter arrows after some beast, its stiffness would be lost by the excessive and continuous strain. ”

“ The shape is no longer so elegant; the articu­lations have less elasticity; the muscles are more feeble; the movements are less light; and in plump women we observe those broken, motions, and in others that stiffness which mark the walk or the dance at that age. ”

“ Sometimes this stiffness begins or soon extends to the muscles of the lower jaw; the throat becomes dry and is painful and gradually the stiffness increases to a continuous contraction, spasm, and extends to the muscles of the trunk and extremities. ”

“ If moved, the general stiffness is at once seen. The patient cannot be turned round in his stall, he may not even be able to turn the neck to one side, and if backed he resists, or accomplishes the movement only with the greatest difficulty. In walking, the limbs are used as stilts with little or no bending of the joints, and if turned, the body is not bent but moved around with difficulty as if one rigid mass. ”

“ I. The first and most serious mechanical error committed on the body by dress is that of tightness, by which pressure is brought to bear upon some particular part. Presuming that an equable general pressure, not extreme in its character, and including the whole body, were applied for fitting purposes, that is to say, for the purpose of indicating outline, no great evil probably would follow from the application of such pressure, provided that it were so adapted as to give with the growth, to yield a certain measure of elasticity, and to permit perfect freedom of motion. ”

“ No matter what part of the human body we examine, we shall find that its mechanical work is performed by means of bony levers. Having seen how the head is moved as a lever of the first order, we are now to choose a part which will show us the plan on which levers of the second order work, and there are many reasons why we should select the foot. It is a part which we are all familiar with; every day we can see it at rest and in action. The foot, as we have already noted, serves as a lever in walking. ”

“ Now, when several muscles are attached to one bone in such a way that they pull in opposite directions, the bone must assume a position in which the tension of all the muscles is balanced, and all these tensions must combine to press together the socketed parts with a certain force, thus evidently contributing to the strength of the socket connection....This balanced position of all the limbs, which thus depends on the elasticity of the muscles, may be observed during sleep, for then all active muscular action ceases. ”

“ From which we conclude, that in pulling there is added to the power of extension the strength of the arms, of the legs, of the back, and even of the chest, if the oblique motion of the body require it. But in pushing, though all the parts were employed, yet the strength of the muscles of the arms is wanting; for to push with an extended arm without motion does not help more than if a piece of wood were placed from the shoulder to the column meant to be pushed down. ”

“ Flexion and Extension.—The muscles are, for the most part, so arranged in pairs, or corresponding sets, that when motion is produced in one direction by one set, there is, opposite to it, another muscle, or group of muscles, which brings the limb back to its place. When they act alternately, a to-and-fro movement results. When a joint is bent, the motion is called flexion ”

“ In this case, there is something transmitted from my hand along the string to the weight in consequence of which the weight moves: that something is a force. I can also move the weight by pushing it with a stick, because force is transmitted along the stick, and makes itself known by producing motion. The archer who has bent his bow and holds the arrow between his finger and thumb feels the string pulling until the impatient arrow darts off. Here motion has been produced by the force of elasticity in the bent bow. ”

“ Every ounce of elastic force in the great, muscular frames was called into action, and there was a profusion of strange, strong language that literally made my flesh to creep, and my hair to stand on end. ”

“ Nor can muscular motion be assimilated with greater plausibility to the attraction of cohesion or elasticity; for in bending a steel spring, as a small sword, a less force is required to bend it the first inch than the second ”

“ Weight.
Fig. 118—Diagram of the foot lever. F. Fulcrum at ankle joint. W. Body weight expressed as pressure against the earth. While the muscle power acts through the distance ab, the fulcrum support (body) is forced through the distance FE. Loss of Muscular Force.—Using a small spring balance for measuring the power, a light stick for a lever, and a small piece of metal for a weight, and arranging these to represent some lever of the body (as the [pg 254] forearm) , it is easily shown that the gain in motion causes a corresponding loss in muscular power. ”

“ If the applied load is not strictly axial, if the strut is not initially straight, if it is subject to any deflexion by transverse forces, or if the modulus of elasticity is not uniform over each cross- section — then loads smaller than the limit which causes instability will produce a certain deflexion which increases with increase of load, and will give rise to a uniformly varying stress of the kind illustrated in figs. ”

“ If the sole of the foot shows at all, it should be from the rear. What is wanting is elasticity. Swinging the arms in walking, which is universal, is absolutely unnecessary, and purely a waste of strength. ”

“ By the word stretchings I mean the stretching of his body and limbs by a slow and gentle convulsion of the extensor muscles; for in all the attacks I never observed the flexores any way affected. — His feelings were frequently so odd that, he said, he could not describe them. He often felt as if his left side, from his head to his waste was empty, and that millions of small bodies were drove up and down with great velocity: which he likened to the shaking of peas in a bladder. ”

“ How is this suspension of the body, at each impulse of the foot, produced? We might at first think that it is the effect of a kind of leap in which the body is projected upward in so violent a manner, by the impulse of the feet, that it would describe in the air a curve, in the midst of which it would attain its maximum elevation from the ground. We may convince ourselves that such is not the case by reference to Fig. 7. The upper line (O) is a tracing of the vertical oscillations in running. ”

“ At the same time, the ligaments of the joints are violently stretched, which must tend to diminish the completeness of the apposition of the joint-surfaces, and thus diminish precision and rapidity of motion. ”

“ The rolling of a stiff is ofttimes an amusing sight, especially when the stiff is helpless and when interference is unlikely. At the first swoop the stiff's money and jewellery go. Then the kids sit around their victim in a sort of pow-wow. ”

“ That thickening of the epidermis on a labourer's palm results from continual pressure and friction, is certain. Those who have not before exerted their hands, find that such an exercise as rowing soon begins to produce a like thickening. ”

“ She saw how no wind left emptiness where it had been, but how the elastic tissue thinned out, spread, gathered together, ran here and there so that no outflow was without its inevitable influence of contraction: the whole sphere of air was a medley of pattern, always rhythmic and interchanging. ”

“ But in life, that fabric of struts is surrounded and interwoven with a complicated system of ties: ligament and membrane, muscle and tendon, run between bone and bone; and the beauty and strength of the mechanical construction lie not in one part or in another, but in the complete fabric which all the parts, soft and hard, rigid and flexible, tension-bearing and pressure-bearing, make up together618. ”

“ The feature that seems to be emphasized is the stumbling, crawling, motion, which as seen in a flow, may be compared to the awkward, ataxic movement of one whose knees are dislocated and leg-bones broken. ”

“ This impetuous motion is accompanied by an instantaneous extension of the body which had bent itself, like a spring or bow, along the back, the joints of the thighs, knees, and feet, and is let off obliquely, that is, upwards and forwards; so that the disposition of the body tending forwards and upwards, makes it describe a great arch when it springs up, which increases the leap. ”

“ In producing the motions of the body, the muscles use the bones as levers. We see an illustration of the first class of levers in the movements of the head. The back or front of the head is the weight to be lifted, the backbone is the fulcrum on which the lever turns, and the muscles at the back or front of the neck exert the power by which we toss or bow the head. ”