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    The bones of the body: their construction, number, nature, power, position, and use.-The joints, ligaments, synovia, etc., etc.HBH 19.1

    25. Of what is the human body composed?HBH 19.2

    Of solids in different degrees of density, and fluids that circulate through them.HBH 19.3

    26. What is the cubical size of the body, and what is the principal element of its composition?HBH 19.4

    The bulk of the body, upon an average, is equal to a cube of a little more than sixteen inches on a side. The principal element of the body is water. The amount of water equals a cube a little more than fourteen inches on a side, or nearly four-fifths of the body.HBH 19.5

    27. What are the solids of the body?HBH 19.6

    The solids of the body are bones, teeth, cartilages, ligaments, muscles, nerves, vessels, viscera, membranes, skin, hair, and nails.HBH 19.7

    28. What are the fluids of the body?HBH 19.8

    The fluids of the body are blood, chyle, lymph, saliva, gastric juice, pancreatic juice, synovia, mucus, and serum. Bile, sweat, and urine are excretions.HBH 19.9

    29. What does a chemical analysis of the body show?HBH 19.10

    It discovers to us that almost the entire bulk of the human body consists of Oxygen, Hydrogen, Nitrogen and Carbon. The bones and teeth are more than half phosphate of lime. The teeth also contain carbonate of lime.HBH 19.11

    30. Are there any other substances found in the body?HBH 19.12

    Yes; very small quantities of phosphorus, sulphur, chlorine, iodine, bromine, potassium, magnesium, iron, aluminum, gold, lead, etc.HBH 19.13

    31. What is the hardest solid in the body?HBH 20.1

    With the exception of the enamel of the teeth, the bones are the hardest solid in the body.HBH 20.2

    32. How are the bones constructed?HBH 20.3

    The bony structure is a dense, sub-fibrous basis, filled with minute cells, and traversed in all directions by branching and connected canals called Haversian, which give room to blood vessels and nerves. These cells are irregular in form and size, and give off numerous branching tubes, which by communicating with each other constitute a very delicate network.HBH 20.4

    33. What is found in the cavities and cells of bones?HBH 20.5

    The internal cavities of long bones, and the canals and cells of others, are lined by a membrane, and filled with an oily substance called medulla, or marrow.HBH 20.6

    34. Are the bones formed of what we eat?HBH 20.7

    Yes; every part of the body is formed of and from what we eat, after the food has been changed into blood. As the blood circulates through the body, certain portions are secreted or separated from it to supply the several solids and fluids of the body.HBH 20.8

    35. Is it then necessary that our food should contain the constituent elements of our bodies?HBH 20.9

    It is. All substances containing these elements, however, are not proper food. Milk and eggs are supposed to contain nearly all the elements in the human body; but it does not follow from this that we should live wholly on milk and eggs, nor that we should eat lime, or drink lime water, because there is lime in our bones. Fruits, grains and vegetables, contain every element composing the human body, and that, too, in a state easy of being appropriated by our system to build up the structures of the body. But more of this under the head of digestion.HBH 20.10

    36. What is the strength of human bones?HBH 21.1

    Human bones, when used as levers, are twenty-two times as strong as sandstone, three and one-half times as strong as lead, nearly two and three-fourths times as strong as elm and ash, and twice as strong as box, yew, and oak timber.HBH 21.2

    37. Does the quality of the food we eat affect the strength and soundness of the bones?HBH 21.3

    It does. If our food is not sufficiently nutritious, or is of too poor a quality, our bones will be liable to be soft and diseased. This is the most effective cause of the rickets. As the bones become softened, by the strength of the muscles the body is drawn into unsightly deformity.HBH 21.4

    38. What other means injure the bones?HBH 21.5

    Too little exercise in the open air, working in mines, working or living in damp, or poorly-lighted places, sleeping in close rooms, or rooms where the air is stagnant or impure, or keeping our bodies, while laboring, constantly bent, or in any posture which prevents the free circulation of the blood, and the natural action of the vital organs; all these injure the strength and health of the bones. Children, especially, should not be confined in any unnatural position, but be allowed to move freely in whatever direction nature may demand.HBH 21.6

    39. How often is it supposed our bones undergo a change?HBH 22.1

    In from one to ten years it is supposed that the entire body, including the bones, undergoes a change. This change is caused by the minute particles that form the body undergoing a state of decay and reproduction. This change, however, is so gradual-particles passing off and others taking their place-that the body, to a great extent, retains its identity through life.HBH 22.2

    40. Where are the bones of the human body placed?HBH 22.3

    They constitute the frame on which the body is built. They give form and strength to the body, support its various parts, and prevent it from sinking by its own weight; they serve as levers for muscles to act upon, and to defend the brain, heart, lungs, and other vital parts, from external injury, and occupy the same position in the body that the frame does in a building. The muscles, nerves, flesh and skin, are placed upon the bones as a carpenter puts boards on the frame to build the house.HBH 22.4

    41. How many bones are there in the human body?HBH 22.5

    The number is variously estimated by different anatomists from 240 to a much larger number. The best authorities, however, give 246 distinct pieces in the body of a grown person.HBH 22.6

    42. How many kinds of bones are there in the human body?HBH 22.7

    Three: long, flat, and irregular. The long appertain to the limbs, the arms, legs, fingers and toes; the flat inclose cavities, as the brain and pelvis; the irregular are formed mostly about the base of the skull, face, trunk, wrist, and instep. All these forms of the bones are requisite for the situations they occupy, and the respective functions they fulfill.HBH 22.8

    43. What is the only bone in the body which is completely ossified, or hardened at birth?HBH 23.1

    It is that bone which is called the petrous, which contains the organs of hearing. The bones do not become solid till the twelfth year of life.HBH 23.2

    44. Are the bones of the young liable to become otherwise injured?HBH 23.3

    Yes; many persons in making their little children sit alone at too early an age, produce in them a crooked spine. In allowing them to stand or walk before the bones of the legs are sufficiently toughened, their legs become crooked, either bandy-legged or knock-kneed, for life. It is for this reason important that great care should be taken while the bones are soft, that they be not misshaped. Children should not be urged to walk. They will try to walk themselves when their bones are sufficiently toughened to walk. The flat-head Indians of North America tie hard pieces of board on the back and front side of the heads of their children till the skull hardens in this shape, which causes the head to have its flattened appearance, which it retains for life.HBH 23.4

    45. Are the bones of old people as strong as those in middle age?HBH 23.5

    No; in most cases the bones of the aged are dry and brittle, hence are more easily broken by a fall than those of younger persons. When the bones of the aged are broken, the process of knitting the bone together, as it is called, goes on, if at all, very slowly. For this reason, it requires two or three times as long a period for one to getHBH 23.6


    about with a broken limb at seventy years of age, as for one at twenty-five or thirty.HBH 24.1

    Figure I

    In Fig. I, we have a human skeleton. a a is the back bone, at the upper part of which is the axis on which rests the atlas, as it is called; b, humerus, long arm bone; c, joint of elbow; d, e, ulna and radius, the two bones of the fore-arm; f, the carpus, or bones of the wrist; g, metacarpus and phalanges, bones of the hands and fingers; h, the joint of the hip; i, the femur, or thigh bone, the longest bone in the body; l, the lower end of the femur or thigh bone, which is enlarged; k, the patella, or knee-pan; m, the tibia; n, the fibula; the two bones of the leg; o, the tarsus, or bones of the heel and instep; p, metatarsus, bones of the foot and toes; r, the thorax, or bones of the chest, ribs, etc.; s s and w, the pelvis; w, the sacrum, a wedge-shaped bone at the lower end of the back bone; x, the sternum, or breast bone; y, the clavicle, or collar bone, which extends across the upper part of the chest, from the upper end of the sternum to the shoulder blade.HBH 24.2

    46. What is the average weight of a human skeleton?HBH 25.1

    About one-tenth the weight of the whole body.HBH 25.2

    47. What are the bones of the human skeleton, and how many are there of each?HBH 25.3

    Bones of the skull 8
    Ear 6
    Face 14
    Teeth 32
    Back, vertebral column 24
    Ribs, twelve pairs 24
    Tongue, os hyoides 1
    Upper extremities, arm, wrist, & fingers 64
    Breast bone, sternum 1
    Pelvis, hip, sacrum, and coccyx 4
    Lower extremities, leg, instep, and toes 60
    Sesamoid-knee pan, and bones in tendons 8
    Total 246

    48. What are the bones of the back called?HBH 26.1

    The vertebral column.HBH 26.2

    49. How many pieces are there in the vertebral column, a a, Fig. I?HBH 26.3

    Thirty-three in the young person, but in advanced life the nine lower pieces unite into two.HBH 26.4

    50. What is each of these pieces called?HBH 26.5

    Vertebra. Twenty-four of these are called the true vertebrae, the rest are called the false vertebrae, which unite to form the sacrum and coccyx; these last are also concerned with the hip bones in the formation of the pelvis or basin at the bottom of the trunk, and constitute the base on which the vertebral column rests. Of the true vertebrae, seven belong to the neck, twelve to the back, and five to the loins; and are accordingly distinguished by the terms cervical, dorsal, and lumbar vertebrae, from the Latin cervix, neck; dorsum, back; and lumbar, loins.HBH 26.6

    51. What is the first cervical vertebra, which supports the head, called?HBH 26.7

    Because it supports the head, it is called the atlas. This is said to be thus named from the tradition that a giant by the name of Atlas supported the earth on his shoulders.HBH 26.8

    52. What is the atlas?HBH 26.9

    It is the ring of bones which allow the head to move sidewise as well as backward and forward to some extent on the second cervical, which is called the axis.HBH 26.10

    53. Are the bones of the vertebrae solid?HBH 26.11

    No; there is a large cavity the whole length of the spinal column for the spinal marrow, and two smaller cavities each side of the spinal marrow, extending down along the back side of the vertebral column, for the spinal cord.HBH 26.12

    54. What do the bones of the spinal column resemble?HBH 27.1

    They have some resemblance to so many rings piled upon one another. This is not an exact resemblance however, for they have several projections from the arch behind; one running directly back, which is called the spine. Two running obliquely backward, with which the ribs form one of their joints of attachment. The vertebrae are therefore so constructed, that when arranged in their proper order, they form both a column of support to the body, and a canal for the spinal marrow. Between all of these bones is interposed an elastic, fibrous cartilage, which, with the surrounding ligaments, unites and binds them to each other in such a manner as to give the column considerable flexibility and elasticity, and at the same time secure to it all the supporting power of a solid bone. Thus it forms a strong upright column, which gives erectness, dignity, and grace to the human body.HBH 27.2

    55. How do many persons injure the shape of the spinal column?HBH 27.3

    By wrong positions in sitting, standing, or lying down. By sitting considerable of the time, as many do, in rocking chairs, or while writing, bent forward, or with one shoulder higher than the other. By these ill-habits, this column becomes bent too far forward, or crooked sidewise, causing either round shoulders, or a dropping of one shoulder lower than the other. Some lie on two or three pillows, so that when they habitually lie upon the side they are in danger of causing this same curvature of the spine. In sitting, you should sit back against the back of the chair, with head erect, shoulders back, and the whole vertebral column to the shoulders resting against the back of the chair. In lying down, whether on the back or side, lie with the body, arms, and limbs straight, and the head elevated not more than four inches. You should habituate yourself to sleeping on either side. Frequently changing from side to side is also beneficial. Never sleep lying upon your face.HBH 27.4

    56. Into how many parts is the skull divided?HBH 28.1

    Four; superior, lateral, inferior, and anterior. The superior is the front and upper portion, or that containing the intellectual brain. The lateral, is the sides. The inferior, the base of the head. The anterior, the face.HBH 28.2

    57. What are the cavities of the skull called in which the eyes are placed?HBH 28.3

    The orbits of the eyes. These are hollow cones for the lodgment of the eyeballs with their muscles, vessels, nerves and glands.HBH 28.4

    58. How many bones are there in the head?HBH 28.5

    Sixty-one, above the upper joint of the neck, including the teeth.HBH 28.6

    59. How many bones are there that give shape to the skull?HBH 28.7

    Eight, and these are united together at their edges. These edges which lap into each other somewhat resemble saw teeth. These ragged pieces of bone uniting the parts of the skull together (see Fig. I) are called sutures, from the Latin sutura, to sew, because they look very much like the seam made by sewing two pieces of cloth with the “over-and-over” style of stitch.HBH 28.8


    60. How many bones are there in the face?HBH 29.1

    Fourteen, besides the teeth.HBH 29.2

    61. Are there any bones in the ear?HBH 29.3

    Yes; there are three bones in each ear, and these assist in conveying sound to the brain.HBH 29.4

    62. Are there any bones in the tongue?HBH 29.5

    Yes; there is one bone at the root of the tongue called os hyoides. It is used to support the tongue and upper part of the larynx, or windpipe.HBH 29.6

    Figure II

    63. What does Fig. II illustrate?HBH 29.7

    It illustrates the formation of the teeth, their nerves, etc. The infant set are in the jaws, while the outlines of the second set are also observable.HBH 29.8

    Keep your eye on this figure while answering the following questions.HBH 30.1

    64. How many teeth has the human being?HBH 30.2

    The permanent teeth are thirty-two in number, sixteen in each jaw.HBH 30.3

    65. How many parts are there to the tooth?HBH 30.4

    There are three parts; called the crown, the neck, and the root. The crown is that part which is seen above the jaw, the neck is that portion clasped by the upper rim of the socket, and the root is that part within the gum and socket, which is fastened to the jawbone.HBH 30.5

    66. Of what are the teeth composed?HBH 30.6

    Of a firm crust, called enamel; the tooth bone proper, called the ivory, and a cortical substance, called cementum. The enamel covers the exposed surface of the crown, and the cementum forms a thin coating over the root of the tooth. These become thinner in old age.HBH 30.7

    67. Are the teeth, like all our other bones, made from our food?HBH 30.8

    They are; and like the other bones, are composed largely of lime, but unlike our other bones, are exposed to the immediate action of the air and foreign substances.HBH 30.9

    68. In what other respects do the teeth differ from the other bones?HBH 30.10

    They are composed of a much harder material. The ivory of the tooth is much harder than bone, and the enamel is still harder.HBH 30.11

    69. What is the use of this enamel?HBH 30.12

    It gives the teeth strength, as well as hardness, for biting, chewing, and grinding the food; it also prevents injury from these operations, and from the action of acids on the bone of the teeth; it also adds much to their beauty.HBH 30.13

    70. If this enamel is broken, does it form on the tooth again?HBH 31.1

    When the enamel is once destroyed it is seldom, if ever, restored again. When it is once broken the teeth are liable to rapid decay. It is important to use our teeth carefully in this respect, and not use them to crack nuts, or bite very hard substances, lest in after time we be deprived of their more important use in grinding our food.HBH 31.2

    71. Are the teeth supplied, like our other bones, with blood vessels and nerves?HBH 31.3

    They are; and as most people have occasion to know, these nerves are endowed with life, and also an exquisite sensibility, which is the more apparent when the teeth become decayed.HBH 31.4

    72. How many teeth has a young child?HBH 31.5

    Twenty; ten in the upper, and ten in the lower jaw.HBH 31.6

    73. What care is necessary in relation to the teeth of children?HBH 31.7

    When a child is from five to seven years of age, the teeth loosen, when they should be immediately removed; otherwise they will prevent the proper formation and regularity of the new and permanent teeth, which are growing under them. Some persons permit their children to eat candies and sweetmeats with their first set of teeth, and manifest but little care for them; but it should be borne in mind that the same nerves and blood-vessels that are connected with the first set of teeth, are at the same time communicating with the embryo forms of the second set, which are forming beneath them. See Fig. II. The nature of the second set in a great measure depends on the nature and care of the first set. Disease of the child’s teeth then may cause them many ills in after life.HBH 31.8

    74. Why is it necessary for the human mouth to be furnished with two sets of teeth?HBH 32.1

    The gradual growth of the body, renders it necessary that our little jaws should be furnished with a set of teeth in childhood, which are too small to fill up our jaws when our system is fully developed, and too small to answer the purposes of mastication through life; and hence the all wise Creator has established a law in our system by which the small teeth of our childhood are removed, and their places supplied with a larger, permanent set, which are better fitted for mastication.HBH 32.2

    75. What is the difference between the first and second sets of teeth?HBH 32.3

    The first teeth, or those of a child, only pass through the gum socket which is fastened to the jaw, while the second set grow out of the jaw itself, between the roots of the first set of teeth; so if the first are not removed, the second set must force their way inward or outward between them.HBH 32.4

    76. How many different kinds of teeth have we?HBH 32.5

    Three; four cutters, or front teeth, in each jaw; two pointers, or eye teeth, in each jaw; and ten grinders, or back, double teeth, in each jaw; half on each side of the face.HBH 32.6

    77. What is the most important use of the teeth?HBH 32.7

    Their leading and most important use is to cut and chew, or grind the food so finely that it may be mixed with the saliva, or the moisture of the mouth, before passing into the stomach.HBH 33.1

    78. If we had no teeth, would we have the pleasure in eating we now enjoy?HBH 33.2

    No; for then our food would need to be mostly liquid or semi-fluid.HBH 33.3

    79. Are the teeth otherwise useful?HBH 33.4

    Yes; they assist the voice in talking, reading aloud, and singing. If a person loses two or three front teeth, he talks, reads, and sings, in a hissing, disagreeable manner. The loss of teeth prevents a person from giving the correct sounds of many letters, and from articulating distinctly.HBH 33.5

    80. Should we not do everything in our power to preserve our teeth?HBH 33.6

    Yes; we should never pick nor scratch them with pins or pocket knives; for these break the enamel. Quill or wooden tooth picks may be useful in removing any particles of food that may not be readily reached by the brush, but metallic tooth picks should never be used.HBH 33.7

    81. In what other ways are the teeth injured?HBH 33.8

    By taking into the mouth food or drink which is either too hot or too cold, by smoking or chewing tobacco, by using acid drinks or fruits which set the teeth on edge. Hot substances taken into the mouth serve more directly and powerfully to destroy the teeth than any other cause which acts immediately upon them.HBH 33.9

    82. Why are the teeth of Europeans generally better than those of Americans?HBH 33.10

    The principal reason is, their food is more simple, and their habits more temperate and uniform, than those of Americans.HBH 33.11

    83. How can we care for the teeth?HBH 34.1

    The teeth should be cleansed with a brush or a soft piece of flannel, and tepid water, after every meal, but more especially before retiring to rest, and again after rising in the morning. Some refined soap may be occasionally used, to remove any corroding substance that may exist around or between the teeth. The mouth should be rinsed after its use. Soft water is always best for the teeth. If the teeth are closely set together, drawing a thread between them occasionally will be of great benefit.HBH 34.2

    84. What is the cause of the pain called “tooth-ache?”HBH 34.3

    When a tooth is so decayed that its inflamed nerve is exposed to the air, it causes tooth-ache. Sometimes food crowded against the bare nerves in eating, produces the same effect.HBH 34.4

    85. What should we do with decayed teeth?HBH 34.5

    If any of our teeth have begun to decay, a dentist should be consulted as soon as possible, and the cavities filled with gold. Natural teeth, if partly filled with gold, are always better than artificial teeth. When teeth are past filling, they should be immediately removed, otherwise they will cause decay in adjoining teeth, give rise to neuralgic pains, or cause maxillary abscess, which is known by a severe and obstinate pain in the face, just below the eye, near the nose. Sometimes this disease causes discharges of offensive matter from the nose, it also produces bad breath, and affects the general health. It may be years in forming, and be mistaken for common tooth-ache.HBH 34.6

    86. What is another great leading cause of the premature decay of teeth?HBH 35.1

    Their disuse. The more the teeth are regularly and properly used for the purposes for which they were intended, that of masticating and preparing the food for the stomach, the more healthy they will be, and the less liable to decay. Experience shows that the teeth decay the most rapidly between the ages of fifteen and thirty. So that youth need to give the most special attention to their teeth.HBH 35.2

    87. Who have generally the best teeth?HBH 35.3

    Those who have the best health. Therefore to assist in preserving the teeth, the stomach and lungs should be kept in as healthy a condition as possible. The proposition we think is correct, that diseases of the nervous system affect the teeth, and also diseased or decaying teeth have a powerful effect upon the general health. The loss of the teeth cripples the natural action of the system-lessens the action of the salivary glands, and to some extent shortens life.HBH 35.4

    88. What are the bones of the chest?HBH 35.5

    The sternum, or breast-bone in front, and the twelve pairs of ribs on the side, and these constitute the thorax. See Fig. I.HBH 35.6

    89. What is the sternum, or breast-bone?HBH 35.7

    It is that bone which lies directly in the central line of the fore part of the chest; its upper end lies within a few inches of the vertebral column, while its inferior extremity projects considerably forward. It is about eight inches in length, and one and a half inches in width.HBH 35.8

    90. What is the form of the ribs?HBH 35.9

    They grow out of the spine, or back bone, on the back side, forming a hoop by meeting and being fastened to the breast bone in front.HBH 36.1

    91. Do all these ribs grow directly to the breast bone?HBH 36.2

    The first or upper seven pairs, grow directly to the sternum. The five lower pairs are called false ribs, and are connected with each other in front by cartilages, or a substance somewhat like bone, but more pliable and spring-like.HBH 36.3

    92. Are all the ribs of one size and shape?HBH 36.4

    No; they increase in length from the first to the eighth, and then diminish in length to the twelfth. In breadth they diminish from the first to the last, except the two lower ones. The first is horizontal and all the rest oblique. The two lower ribs are called floating ribs.HBH 36.5

    93. Of what use are the ribs?HBH 36.6

    They are the frame-work of that part of the human trunk termed the chest, in which the lungs and heart are deposited for safe keeping.HBH 36.7

    94. Is it important to care for this frame-work?HBH 36.8

    It is. If we wear our clothing too tight, we diminish the size of the chest, crowd the lungs, heart, and other organs, and hinder their healthy action. By sitting, or standing in a stooping posture, the lower end of the sternum is crowded upon the stomach, which injures and weakens it. Men or women who wear tight clothing over the lower ribs must injure their health.HBH 36.9

    95. What do the bones of the upper extremities comprise?HBH 36.10

    They are the clavicle, or collar bone; the scapula, or shoulder blade, a large, flat, triangular bone back of the shoulder; the humerus, or armHBH 36.11


    bone; the ulna and radius, or bones of the forearm; these two move at the elbow similar to a door hinge. The word ulna is Latin, and means an ell. This bone is so named because in early times it was used as the measure of an ell; the carpus, or the eight bones in two rows across the wrist; the metacarpus, or five bones of the palm of the hand; the phalanges, or fourteen bones of the fingers.HBH 37.1

    Figure III

    96. What does Fig. III represent?HBH 37.2

    The carpus. 1, lower end of the radius; 2, lower end of the ulna; 3, connecting cartilage; S L C P, first row of bones in the wrist; T T M M, second row of bones; 4,5,6,7, and 8, the five bones of the palm of the hand, to the end of which the phalanges, or finger bones are attached.HBH 37.3

    97. What is the pelvis?HBH 37.4

    The pelvis is that part of the human body which is fixed in relation to the rest, and about which all the rest move; beneath it the lower extremities walk, and above it the back bone is movable. It is a collection of bones at the lower end of, and attached to, the vertebral column. The upper part of it serves as a support to the abdominal organs. To the lower sides of it the thigh bones are attached. See s s and u, Fig. I.HBH 37.5

    98. What are the bones of the lower extremities?HBH 38.1

    The femur, or thigh bone, which is the longest bone in the body; the patella, or knee-pan, which is heart-shaped in figure, and is connected with the lower portion of the thigh bone; tibia and fibula, or the bones of the leg; the tarsus, or seven bones of the ankle; the metatarsus, or the five bones of the foot; the phalanges, or fourteen bones of the toes. The bones of the tarsus and the metatarsus correspond, somewhat, to those of the carpus and metacarpus of Fig. III.HBH 38.2

    99. Are there any other bones in the human body?HBH 38.3

    Yes; there are what are called sesamoid bones. These are formed in tendons, and are a sort of pulley on which the tendons of the body play. They are also placed over joints. The knee-pan is one of them. There is one of them on the joint of the thumb, and of the little finger, and in other parts.HBH 38.4

    100. Are the bones of the body mostly in pairs?HBH 38.5

    All the two hundred and forty-six bones of the body, except thirty-four, are found in pairs, or one on each side of the body.HBH 38.6

    101. What is the connection between any two bones called?HBH 38.7

    A joint or articulation. It is by means of these joints that the various motions of the bones are easily made.HBH 38.8

    102. How many joints are there in the human body?HBH 38.9

    Over two hundred, all perfectly adapted to their various positions and work.HBH 38.10

    103. How many motions can be made by the joints?HBH 38.11

    The motions of the joints are four. The first is where the bones slip over one another, which is the case in all joints. The second is angular movement, as up and down, right and left, or such motions as you can make with your fore finger sidewise, and by bending and straightening it out. The third motion is circular. It consists in moving the bone around in a circle with the joint as a center, such as you make in whirling your arm around the shoulder joint. The fourth motion is called rotation, such as the moving of the atlas on the axis in the neck.HBH 38.12

    104. What is the construction of a movable joint?HBH 39.1

    The opposing surfaces are coated by an elastic substance called cartilage, this is lubricated-oiled-by a fluid called synovia, which is secreted in an enclosed membrane or bag, called synovial.HBH 39.2

    105. How are the bones held firmly together?HBH 39.3

    By bands of glistening fibers, called ligaments. These are mostly short, and attached only to the enlarged extremities of the bones. In such joints as that of the shoulder and hip, there is between the ends of the bones what is called the round ligament. It is a bundle of fibres in the form of a cord. It is used to keep the head of the bone from slipping out of the socket, and at the same time it allows the most perfect freedom of motion.HBH 39.4

    106. How are the joints kept in their places, or the bones from getting out of joint when they are moved?HBH 39.5

    There are ligaments formed about all the joints, sometimes constituting bands of various breadths and thicknesses, and sometimes layers of these bands are extended around the joints. These serve the same purpose in the human frame as the pins in a frame building. Instead, however, of clumsy joints being made and pinned together, a few tough fibres and membranes, secure at once, in a most perfect manner, every portion of the frame, and provide at the same time means for its lubrication. Some of the ligaments are situated in the joint, like a central cord or pivot, and some surround it like a hood.HBH 39.6

    107. Where are the ligaments principally found?HBH 40.1

    The ligaments bind the lower jaw to the temporal bones, the head to the neck, extend the whole length of the back bone in powerful bands, both on the outer surface, and within the spinal canal, and from one spinal process to another; and bind the ribs to the vertebrae, and to the spinal projection behind, and to the breast bone in front, and this to the collar bone, and this to the first rib and shoulder blade, and this last to the bone of the upper arm at the shoulder joint, and this to the two bones of the fore-arm at the elbow joint, and these to the bones of the wrist, and these to each other, and those of the hand, and these last to each other and those of the fingers and thumb. In the same manner they bind the bones of the pelvis together, and the hip bones to the thigh bone, and this to the two bones of the leg and knee-pan, and so on to the ankle, and foot, and toes, as in the upper extremities.HBH 40.2

    108. What can you say in general of the cartilages and ligaments?HBH 40.3

    They unite, and bind the whole bony system together in a powerful manner, so as to possess in a wonderful degree mobility and firmness. The ligaments and cartilages are in health destitute of animal sensibility. They are soft and yielding in early life, and become more dry, rigid, and inflexible in old age.HBH 40.4

    109. What other useful contrivance is connected with the joints?HBH 41.1

    In all the movable joints the articulating surfaces of the bones are covered with dense and highly-polished cartilages, by which means the joints are enabled to act with great ease and little friction, and at the same time it constitutes a cushion which breaks in a great measure the sudden jar which otherwise would be felt in the head, when walking or suddenly moving the limbs. It protects the brain in the same manner that the springs of a carriage prevent a sudden jolt. Cartilage is also employed separately from the bones in forming some of the cavities, etc., as the larynx, wind-pipe, part of the nose, etc.HBH 41.2

    110. How many kinds of joints are there?HBH 41.3

    Three: fixed, or such as the joints of the skull and upper jaw, teeth and vomer; 1The gristly substance between the nostrils is attached to what is called the vomer. movable, such as the shoulder, hip, elbow, wrist, knee, ankle, carpus, and tarsus; intermediate, or such joints as those in the vertebral column.HBH 41.4

    111. Why are the bones of the body mostly cylindrical, or hollow?HBH 41.5

    To secure great strength with as little material as possible. Were the bones of the human skeleton made solid, it would be so heavy and cumbersome that it would require a larger amount of muscles, making the body unwieldy, and thus depriving it of its rapidity and ease of motion.HBH 41.6

    112. Is there any other peculiarity in the bones not already mentioned?HBH 41.7

    The bones are closely covered with a very firm, whitish-yellow membrane, very smooth, this is called the periosteum. This membrane encloses the vessels which carry nutriment into the bones. It is to this periosteum that the ligaments and tendons are attached, as they cannot fasten to the bone itself. In fever sores and felons the disease begins in most cases in the periosteum of the bone, or the tendons, but if not checked it soon affects the bone itself. Cool baths, or a cool wet bandage upon the affected part during its fevered condition is good. Felons may many times be driven away by keeping the affected part immersed a long time in hot water. But much time and suffering can be saved by cutting a free gash through the felon into the bone through the periosteum. Cut a gash an inch long, at least.HBH 41.8

    113. Are there other diseases, or difficulties with the joints, or bones, that we should guard against?HBH 42.1

    Yes; strains of joints, and dislocations, many times caused by wrestling. This is a dangerous exercise, and should give place to milder sport. Inflammation in sprains should be allayed with the cool wet bandage, covered, of course, by dry flannel. Violent jerking of the arms in gymnastics should be avoided, as it is liable to cause synovitis, or disease of the joints.HBH 42.2


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