The Skeleton (1952)

the human body frame is an amazing assembly of pillars and columns of rings and arches of bridges and supports all movable all designed for maximum efficiency for work without interruption for many many years from the times of the games in ancient olympia to modern athletic contests man has tested the power and endurance of his body in stiffest competition in the quest for more knowledge about his own body man tried to find out how each species adapts itself to the environment he recognized that plants developed special cells and fibers that hold up their beautiful flower and heads he found that animals have different types of support some have an outside support like the sponge the coral the clam they are enclosed in their houses but the vertebrates the fish the reptiles the birds and the mammals have an internal body frame which gives them a greater freedom of motion and among the mammals the human species is the only one that developed a frame which holds it up right and gives it strength and mobility on the ground in the water in climbing jumping or running some 200 bones of every conceivable size and shape moved by some 700 muscles are ready to perform feats of great skill and follow every command of a highly developed nervous system each of the 200 bones of the human skeleton has a specialized function to perform but all the bones together give the body its shape at the same time many of the bones protect and support the organs of the body the ribs protect the lungs the breastbone shields the heart the pelvic girdle with a part of the spinal column protects the lower abdominal cavity the pelvic girdle also provides the base for both legs the bones of the cranium are thick and firmly connected to protect the most important of all organs the brain and the delicate sensory organs such as the eyes and ears the spinal cord this sensitive and all important origin is guarded from injury by small bones or vertebra which at the same time provide firm but flexible support for the top part of the body to permit the body to move freely the human skeleton has a number of joint each serving a special purpose the elbow joint resembles a hinge and is called the hinge joint a hinge joint allows movement in one direction only but with considerable pulling power the knee bones also function like hinges on the door the moving x-ray picture demonstrates this one-sided motion of the hinge joint of the knee the shoulder joint gives considerable freedom to the arm which can rotate in several directions such a joint is called a ball and socket joint just like the arm at the shoulder the legs at the hit can move nearly in every direction the ball and socket joint is so designed that it allows a rotary motion in several directions the wrist can also move in several directions but the wrist motion is achieved by another type of joint called a gliding joint because the wrist ones glide over each other as the wrist moves up and down or sideways bones could not stand the friction and tension demanded of them if it were not for constant lubrication every movement of the joints is lubricated by a secretion called the synovial fluid this fluid is secreted by membranes located at the joint ends of bones the synovial fluid and the cartilage of the joints provide frictionless motion the size of bones varies with the function they have to perform bones grow along lines of stress a well-developed shin bone for instance can support 20 times its normal load however man is not born with a hard and strong skeleton bones develop gradually out of a jelly-like matter this process begins during the second month of the embryo here is roughly how this is accomplished at those points in the embryo where connective tissue is subjected to stress and strain fibers are pressed closer together and first form cartilage under the microscope cartilage cells appear as round bodies embedded in an ember like jelly let's go in closer bone develops gradually as blood vessels penetrate into the cartilage these blood vessels are accompanied by young connective tissue cells which absorb the jelly-like mass around the cartilage cells the bloodstream brings calcium to the new cells they mix the calcium with the jelly into bone substance the connective tissue crowds the cartilage cells out of their former positions the cartilage cells withdraw and take up new positions further away this process of gradual retreat of cells lengthens the bones on each end and the skeleton grows longer and thicker in other words the individual grows as soon as the child begins to stand up his legs must support him the cartilage was only a temporary scaffold which now must give way to a firm and strong boom matter the weight of the child presses upon the bones of the skeleton especially on the legs weight is distributed along definite lines of stress cartilage and newly developed bone matter are stimulated to grow together along these lines of stress wherever the cells have not been under stress they gradually degenerate and disappear leaving an internal bone structure of spongy character which makes the bones light but strong capable of holding up the weight of the body just as the network of slender steel girders holds up a heavy roof or a bridge the structure of bone is extremely complex a greatly magnified view would reveal that bone walls are composed of tiny tubes called haversian systems a still closer view of one such tube would disclose a tiny blood vessel in the center it gives nourishment to thousands of bone cells connected with each other in spider-like fashion by many minut canals the bone forming cells are encased in their shells and surrounded by a cement-like mass of collagen fibers and calcium the bone forming cells are arranged in rings around the central canal through which the blood vessel grows the cells produce calcified bone matter with which they first surround themselves then they produce more abut to fortify the structure around themselves until they are completely imprisoned in it leaving only an opening for a tiny capillary which then brings them food from the central blood source thousands of tubes closely knit together form the bone all bones of the skeleton large and small developed in the same way they are composed of the same organic and inorganic matter all bone consists of mineral salts and living matter it is easy to demonstrate the mineral and tissue contents of the bone some asses will dissolve most of the mineral matter out of the bone leaving only the bone substance the general appearance of the bone has not changed but now the bone has no rigidity it bends without breaking burning removes all living tissue from the bone one light stroke will chip it again the shape of the bone has not been altered much but it has lost all elasticity the minerals enter the body with food and the blood carries them into the bone tissue in childhood and adolescence the diet must be particularly balanced to ensure adequate mineral supply milk is a natural source of minerals for all young mammals but minerals are not enough certain vitamins as polly vitamin D are necessary for the process of ossification just as bones develop along the line of greatest stress so ligaments and joints develop through constant exercise with exercise the spinal column loosens up to allow considerable freedom of motion forward and backward and to both sides it is important to keep it in good shape because the backbone is the axis of the skeleton and yet few people have perfectly shaped spy so ligaments and joints develop through constant exercise with exercise the spinal column loosens up to allow considerable freedom of motion forward and backward and to both sides it is important to keep it in good shape because the backbone is the axis of the skeleton and yet few people have perfectly shaped spines round backs can be seen everywhere sometimes well-formed spines get bent out of shape when children carry loads that are too heavy for them but round and hollow backs are mostly the result of bad habits the spinal column should neither be misused nor condemned to inactivity lack of exercise is one of the most frequent causes of a weak spine high heels can also force the spine out of shape the best form of exercise for the spinal column is carrying a moderate load on the head balancing a load on the head forces all parts of the spinal column to become active and it develops strength and flexibility we have seen that bones develop out of soft cartilage during the years of growth proper food gives the body all the essential building materials for a healthy frame proper exercise influences the size and strength of the bone once developed the body frame needs to be kept strong and healthy by good posture by constant use of all the joints tendons and ligaments by wearing proper clothes and especially footwear and by frequent exercise in fresh air in short by developing and keeping up this wonderful framework with which Nature has endowed us when given proper care the human body is capable of meeting all the exigencies of daily living but it is up to everyone to develop the potentialities of his own body frame in order to enjoy a richer a healthier life you I