Musculature

“ Making the Muscles Strong.—No persons use all of the five hundred muscles in the body every day. In slow walking only about twenty muscles are used, while in running more than four times that number are called into action. Muscles which are not used get lazy and weak.
Every time a muscle is made to act the blood vessels enlarge and bring to it more blood to supply food. The more food the muscle has the stronger it grows. The right arm is used more than the left in most persons. ”

“ The muscles are like the various bits of machinery which go to make up a steam engine. In performing their work they produce heat and motion. The fuel which supplies this force is taken into the body as food, prepared for use in the intestinal tract, and from there carried by the blood to be stored up in the muscles and various tissues as latent force. Through the circulation of the blood the whole body is heated by muscular exercise. It stands to reason that continual exercise of a certain kind will develop certain muscles. ”

“ This perfect equilibrium involves in turn a condition of the muscles in which they are transformed from a dead weight to a living force. In this condition there is said to be a complete connection of all the muscles with the center of gravity; independent motions and independent reactions are eliminated, and a combined force is instantly brought to bear upon whatever work is required. The spine is perfectly straight, the waist muscles firm, and the weight, in the standing posture, is supported upon the balls of the feet. ”

“ The striated muscles, as a [pg 260] rule, are attached to the mechanical devices found in the skeleton, and bring about the voluntary, movements. The non-striated muscles surround the parts on which they act, and produce involuntary movements. Both, however, are under the control of the nervous system. To bring about the opposing movements of the body, the striated muscles are arranged in pairs; and to increase their motion, the bones are used as levers. Physical exercise is necessary both for the development of the muscles and for the health and vigor of the entire body. ”

“ When the muscles contract, they become shorter; but what is lost in length is gained in breadth and thickness, so that their actual volume remains the same. Muscles alternately contract and relax, and thus act upon the bones. The economy of muscular power thus displayed is truly remarkable. In easy and graceful walking, the forward motion of the limbs is not altogether due to the exercise of muscular power, but partly to the force of gravity, and only a slight assistance of the muscles is required to elevate the leg sufficiently to allow it to oscillate. ”

“ What you feel, is a muscle (mŭs ́sl) , and it works your joints very much as the rubber strap works the hinge of the door.
One end of the muscle is fastened to the bone just below the elbow joint; and the other end, higher up above the joint.
When it tightens, or contracts, as we say, it bends the joint. When the arm is straightened, the muscle returns to its first shape.
There is another muscle on the outside of the arm which stretches when this one shortens, and so helps the working of the joint.
Every joint has two or more muscles of its own to work it. ”

“ Structure of Voluntary Muscles. The main substance which clothes the bony framework of the body, and which forms about two-fifths of its weight, is the voluntary muscular tissue. These muscles do not cover and surround the bones in continuous sheets, but consist of separate bundles of flesh, varying in size and length, many of which are capable of independent movement.
Each muscle has its own set of blood-vessels, lymphatics, and nerves. It is the blood that gives the red color to the flesh. ”

“ The Muscles—Flexion and Extension—The Tendons—Contraction—Physical Strength—Necessity for Exercise—Its Effects—Forms of Exercise—Walking—Riding—Gymnastics—Open-air Exercise—Sleep—Recreation.
1. What are the muscles? Their number? The design of most of them? Of a few?
1. The Muscles.— The great mass of the body external to the skeleton, is composed of the flesh, or Muscles, which largely determines its outline and weight. The muscles are the organs of motion. ”

“ Some muscles assist one another in their action, while others have different actions; according to their shapes, the course of their fibres, and the structure of the parts they move.
According to the shape and nature of the bones to be moved, and of the motions to be performed, the muscles are either long, or short; slender, or bulky; straight, or round. Where a great motion is required, as in the leg, or arm, the muscles are long; where a small motion is necessary, they are short; for a strong motion they are thick, and for a weak one slender. ”

“ How the Muscles do their Work.—A tiny nerve [Pg 143] thread runs from the spinal cord or brain to every muscle thread. Messages sent through the nerve threads to the muscles make them act. A muscle can act in only two ways (Fig. 84) . It can become shorter or longer. When it gets shorter, we say it contracts. When it stretches out, it is said to relax.
A muscle cannot contract more than one fourth of its length. To pull the forearm up, the brain sends a message to the muscle fixed by one end at the shoulder and by the other end to a bone at the elbow. ”

“ The arm and chest and dorsal muscles are the ones that must be developed, and these may best be strengthened by work on the chest weights, rope-climbing, dipping on the parallel bars, and by using the travelling parallels. ”

“ Can he predict, with all his learning, that if a certain muscle is drawn up in a particular manner, it will present a particular appearance in a different part of the arm or leg, or bring out other muscles, which were before hid, with certain modifications? ”

“ The muscle, directly that “something” comes to it along its nerves, contracts, shortens, and grows thick; it rises up in the arm; its lower tendon pulls at the radius; the radius with the ulna moves on the fulcrum of the humerus at the elbow-joint, and the arm is bent. ”

“ ANATOMY OF THE MUSCLES.
150. The MUSCLES, by their size and number, constitute the great bulk of the body, upon which they bestow form and symmetry. In the limbs, they are situated around the bones, which they invest and defend, while they form, to some of the joints, their principal protection. In the trunk, they are spread out to enclose cavities, and constitute a defensive wall, capable of yielding to internal pressure, and reassuming its original state.
151. In structure, a muscle is composed of fas-cic ́u-li (bundles of fibres) of variable size. ”

“ The muscles at f, are those which enable us to turn the hand and arm outward. Every different motion of the arm has one muscle to produce it, and another to restore the limb to its natural position. Those muscles which bend the body are called flexors ”

“ Both evidently derive the principle of the activity that marks them from the same external and internal media; but, while the muscle, a mechanical organ, is limited to the obedient transformation of the force assigned to it, under the form of heat, into a measurable amount of work, the nerve, a vital organ, remains impenetrable and inaccessible to our calculations, and exerts its characteristic and sovereign powers in its own way, through a series of operations that escape all estimates of their force and heat. On the part of the muscular system, every thing can be measured ”

“ Why does the muscle contract when that something reaches it? We must be content to say that it is the property of the muscle. But it does not always possess this property. Suppose you were to tie a cord very tightly around the top of the arm close to the shoulder. If you tied it tight enough the arm would become pale, and would very soon begin to grow cold. ”

“ Moreover, we know that all the movements of the limbs depend on the muscles, and that these muscles are opposed to one another in such a manner, that when one of them shortens, it draws along the part of the body to which it is attached, and so gives rise to a simultaneous elongation of the muscle which is opposed to it. ”

“ 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. ”

“ To a gradually increasing extent, the contracting force, instead of being withdrawn when the muscle is inactive, remains; and, as we have already seen, an arm or leg that should be passive is lifted, and the muscles are found to be contracted as if for severe action. ”

“ For example, the strongest muscle in the body is that by which one rises on the toes. This muscle operates by pulling upward at the back of the heel. If it were located right at the ankle, where it would have to be if attached directly to the place where its force is exerted, the resulting clumsiness can easily be imagined. ”

“ These cases are generally accompanied by round shoulders and flat chest, protrusion of the abdomen, and rotation of the vertebræ.
A muscle can be developed only by the active contraction and relaxation of its fibers. Continuous tension quickly tires and lowers its tone, so that exercises given for increasing muscular power should be comparatively quick and frequently repeated, while those that aim at the stretching of muscles and ligaments should be slow and long maintained. ”

“ The muscles should be used, in order that the size and strength of these organs may be adequate to the demand made upon them. It is a law of the system that the action and power of an organ are commensurate, to a certain extent, with the demand made upon it; and it is a law of the muscular system that, whenever a muscle is called into frequent use, its fibres increase in thickness within certain limits, and become capable of acting with greater force ”

“ From these facts, as well as from the great force with which the muscle contracts, one must conclude that the muscle is a transformer of energy—that within its protoplasm, chemical changes take place whereby the potential energy of oxygen and food is converted into the kinetic energy of motion.
Fig. 113—Capillaries of muscles. Plan of Using Muscular Force.—Two difficulties have to be overcome in the using of muscular force in the body. The first of these is due to the fact that the muscles exert their force only when they contract. They can pull but not push. ”

“ That the muscles of the arm, that all muscles in fact should be in a state of efficiency is highly desirable, but in a sedentary life, in the life for which exercises are most obviously useful, it is the large muscle-areas, the muscles which the stillness of sitting tends to degenerate, that should be kept up to the scratch. ”

“ In most instances, the muscles may act from either extremity. The muscles are divided into the Voluntary, or muscles of animal life, and the Involuntary, or muscles of organic life. There are, however, some muscles which cannot properly be classified with either, termed Intermediate. The Voluntary Muscles are chiefly controlled by the will, relaxing and contracting at its pleasure, as in the motion of the eyes, mouth, and limbs. The fibers are of a dark red color, and possess great strength. ”

“ Experiment 20. Repeat the same experiment with other muscles. With the right hand grasp firmly the extended left forearm. Extend and flex the fingers vigorously. Note the effect on the muscles and tendons of the forearm. Grasp with the right hand the calf of the extended right leg, and vigorously flex the leg, bringing it near to the body. Note the contractions and relaxations of the muscles.
70. Arrangement of Muscles. Muscles are not connected directly with bones. The mass of flesh tapers off towards the ends, where the fibers pass into white, glistening cords known as tendons. ”

“ A blacksmith swings a heavy hammer with his right arm, and that arm becomes very large and strong. If we wish our muscles to grow large and strong, so that our bodies will be healthy and vigorous, we must take plenty of exercise. ”

“ Every muscle, in fact, consists in the first place of a mass of muscular substance. This muscular substance is made up of an immense number of soft strings or fibres, all running in one direction and done up into large and small bundles. At either end of the muscle these soft muscular fibres are joined on to firmer but thinner fibres of connective or fibrous{29} tissue. And these thinner but firmer fibres make up the cord or band of tendon with which the muscle finishes off at either end. ”

“ I cannot at present tell you anything about the muscles, except that it is by their means that we move arms, legs, head, eyes—every part of the body, for bones cannot move of themselves, but are acted on by the muscles. ”

“ Further, inasmuch as muscular movement is one of the chief ends, or the most important means to the chief ends of animal life, we find the animal body abounding in motor mechanisms, in which the prime mover is muscular contraction, while the machinery is supplied by complicated arrangements of muscles with such indifferent tissues as bone, cartilage, and tendon. ”