A Treatise on Anatomy, Physiology, and Hygiene Part 7

120. To give a clear idea of the relative uses of the bones and muscles, we will quote the comparison of another, though, as in other comparisons, there are points of difference. The "bones are to the body what the masts and spars are to the s.h.i.+p,--they give support and the power of resistance. The muscles are to the bones what the ropes are to the masts and spars. The bones are the levers of the system; by the action of the muscles their relative positions are changed. As the masts and spars of a vessel must be sufficiently firm to sustain the action of the ropes, so the bones must possess the same quality to sustain the action of the muscles in the human body."

121. Some of the bones are designed exclusively for the protection of the organs which they enclose. Of this number are those that form the skull, the sockets of the eye, and the cavity of the nose. Others, in addition to the protection they give to important organs, are useful in movements of certain kinds. Of this cla.s.s are the bones of the spinal column, and ribs. Others are subservient to motion. Of this cla.s.s are the upper and lower extremities.

119-128. _Give the physiology of the bones._ 119. How may the bones be considered? 120. To what may the bones be compared? 121. Give the different offices of the bones.

122. The bones are subject to growth and decay; to removal of old, useless matter, and the deposit of new particles, as in other tissues.

This has been tested by the following experiment. Some of the inferior animals were fed with food that contained madder. In a few days, some of the animals were killed, and their bones exhibited an unusually reddish appearance. The remainder of the animals were, for a few weeks, fed on food that contained no coloring principle. When they were killed, their bones exhibited the usual color of such animals.

The coloring matter, which had been deposited, had been removed by the action of the lymphatics.

123. The extremities of the bones that concur in forming a joint, correspond by having their respective configurations reciprocal. They are, in general, the one convex, and the other concave. In texture they are porous, and consequently more elastic than if more compact.

These are covered with a cus.h.i.+on of cartilage. The elastic character of these parts acts as so many springs, in diminis.h.i.+ng the jar which important organs of the system would otherwise receive.

124. The synovial membrane secretes a viscous fluid, which is called _syn-ovi-a_. This lubricating fluid of the joints enables the surfaces of the bones and tendons to move smoothly upon each other, thus diminis.h.i.+ng the friction consequent on their action.

_Observations._ 1st. In this secretion is manifested the skill and omnipotence of the Great Architect; for no machine of human invention supplies to itself, by its own operations, the necessary lubricating fluid. But, in the animal frame, it is supplied in proper quant.i.ties, and applied in the proper place, and at the proper time.

122. What is said of the change in bones? How was it proved that there was a constant change in the osseous fabric? 123. What is said of the extremities of the bones that form a joint? 124. What is synovia? Its use? What is said of this lubricating fluid?

2d. In some cases of injury and disease, the synovial fluid is secreted in large quant.i.ties, and distends the sac of the joint. This affection is called dropsy of the joint, and occurs most frequently in that of the knee.

125. The function of the ligaments is to connect and bind together the bones of the system. By them the small bones of the wrist and foot, as well as the large bones, are as securely fastened as if retained by clasps of steel. Some of them are situated within the joints, like a central cord, or pivot, (3, fig. 26.) Some surround it like a hood, and contain the lubricating synovial fluid, (8, 9, fig. 25,) and some in the form of bands at the side, (5, 6, fig. 23.)

[Ill.u.s.tration: Fig. 25. 8, 9, The ligaments that extend from the hip-bone (6) to the femur, (5.)]

[Ill.u.s.tration: Fig. 26. 2, The socket of the hip-joint. 5, The head of the femur, which is lodged in the socket. 3, The ligament within the socket.]

126. By the ligaments the lower jaw is bound to the temporal bones, and the head to the neck. They extend the whole length of the spinal column, in powerful bands, on the outer surface, between the spinal bones, and from one spinous process to another. They bind the ribs to the vertebr, to the transverse process behind, and to the sternum in front; and this to the clavicle; and this to the first rib and scapula; and this last to the humerus.

What is the effect when the synovial fluid is secreted in large quant.i.ties? 125. What is the function of the ligaments? 126. Mention how the bones of the system are connected.

127. They also bind the two bones of the fore-arm at the elbow-joint; and these to the wrist; and these to each other and to those of the hand; and these last to each other and to those of the fingers and thumb. In the same manner, they bind the bones of the pelvis together; and these to the femur; and this to the two bones of the leg and patella; and so on, to the ankle, foot, and toes, as in the upper extremities.

[Ill.u.s.tration: Fig. 27. 1, A front view of the lateral ligaments of the finger-joints. 2, A view of the anterior ligaments (_a_, _b_,) of the finger-joints. 3, A side view of the lateral ligaments of the finger joints.]

128. The different joints vary in range of movement, and in complexity of structure. Some permit motions in all directions, as the shoulder; some move in two directions, permitting only flexion and extension of the part, as the elbow; while others have no movement, as the bones of the head in the adult.

Explain fig. 27. 128. Describe the variety of movements in the different joints.

[Ill.u.s.tration: Fig. 28. 1, 1, The spinal column. 2, The skull. 3, The lower jaw. 4, The sternum. 5, The ribs. 6, 6, The cartilages of the ribs.

7, The clavicle. 8, The humerus. 9, The shoulder-joint. 10, The radius.

11, The ulna. 12, The elbow joint. 13, The wrist. 14, The hand. 15, The haunch-bone. 16, The sacrum. 17, The hip-joint. 18, The thigh-bone. 19, The patella. 20, The knee-joint. 21, The fibula. 22, The tibia. 23, The ankle-joint. 24, The foot. 25, 26, The ligaments of the clavicle, sternum, and ribs. 27, 28, 29, The ligaments of the shoulder, elbow, and wrist. 30, The large artery of the arm. 31, The ligaments of the hip-joint. 32, The large blood-vessels of the thigh. 33, The artery of the leg. 34, 35, 36, The ligaments of the patella, knee, and ankle.]

_Note._ Let the pupil, in form of topics, review the anatomy and physiology of the bones from fig. 28, or from anatomical outline plates No. 1 and 2.

CHAPTER VII

HYGIENE OF THE BONES.

129. _The bones increase in size and strength by use, while they are weakened by inaction._ Exercise favors the deposition of both animal and earthy matter, by increasing the circulation and nutrition in this texture. For this reason, the bones of the laborer are dense and strong, while those who neglect exercise, or are unaccustomed to manual employment, are deficient in size, and have not a due proportion of earthy matter to give them the solidity and strength of the laboring man.

_Observation._ The tendons of the muscles are attached near the extremities of the bones. Exercise of the muscles increases the action of the vessels of that part to which the tendons are attached, and thus increases the nutrition and size of this portion of the bone.

Hence the joints of an industrious mechanic or farmer are larger than those of an individual who has not pursued manual vocations.

130. _The gelatinous bones of the child are not so well adapted for labor and severe exercise as those of an adult._ 1st. They are liable to become distorted. 2d. They are consolidated by the deposition of earthy material before they are fully and properly developed. If a young animal, as the colt, be put to severe, continued labor, the deposition of earthy matter is hastened, and the bones are consolidated before they attain full growth. Such colts make small and inferior animals. Similar results follow, if a youth is compelled to toil unduly before maturity of growth is attained. On the other hand, moderate and regular labor favors a healthy development and consolidation of the bones.

129-148. _Give the hygiene of the bones._ 129. What effect has exercise upon the bones? What effect has inaction? Why are the joints of the industrious farmer and mechanic larger than those of a person unaccustomed to manual employment? 130. Give the first reason why the bones of the child are not adapted to severe exercise. The second reason.

131. _The kind and amount of labor should be adapted to the age, health, and development of the bones._ Neither the flexible bones of the child nor the brittle bones of the aged man are adapted, by their organization, to long-continued, and hard labor. Those of the one bend too easily, while those of the other fracture too readily. In middle age, the proportions of animal and earthy matter are, usually, such as to give the proper degree of flexibility, firmness, and strength for labor, with little liability to injury.

132. _The imperfectly developed bones of the young child will not bear long-continued exertions or positions without injury._ Hence the requisitions of the rigid disciplinarian of schools, are unwise when he compels his pupils to remain in one position for a long time. He may have a "quiet school;" but, not unfrequently, by such discipline, the const.i.tution is impaired, and permanent injury is done to the pupils.

133. _The lower extremities, in early life, contain but a small proportion of earthy matter_; they bend when the weight of the body is thrown upon them for a long time. Hence, the a.s.siduous attempts to induce children to stand or walk, either naturally or artificially, when very young, are ill advised, and often productive of serious and permanent evil. The "bandy" or bow legs are thus produced.

What effect has moderate, regular labor upon the growing youth? 131.

What remark respecting the kind and amount of labor? At what age are the bones best fitted for labor? 132. What effect has long-continued exertions or positions on the bones of a child? What is said of the requisitions of some teachers, who have the famed "quiet schools"?

133. Why should not the child be induced to stand or walk, either naturally or artificially, at too early an age?

134. _The benches or chairs for children in a school-room should be of such a height as to permit the feet to rest on the floor._ If the bench is so high as not to permit the feet to rest upon the floor, the weight of the limbs below the knee may cause the flexible bone of the thigh to become curved. The child thus seated, is inclined to lean forward, contracting an injurious and ungraceful habit. Again, when the feet are not supported, the child soon becomes exhausted, restless, and unfit for study. In the construction of a school-room, the benches should be of different heights, so as to be adapted to the different pupils, and they should also have appropriate backs.

[Ill.u.s.tration: Fig. 29. The position a.s.sumed when the seat is of proper height, and the feet supported.]