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 54 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.