44 



Life and Health 



* 64. How the Growth of Bones may be modified. Bones, 

 as we have seen, are the seat of active vital processes through- 

 out life, except perhaps in extreme old age. The final 



knitting together of the ends of 

 some of the bones with their 

 shafts does not occur until some- 

 what late in life. For example, 

 the separate bones of the sacrum 

 do not fully knit into one solid 

 bone until the twenty-fifth year. 

 Hence the bones of young per- 

 sons should not be subjected to 

 the risk of undue violence from 

 injudicious physical exercise, as 

 in rowing, baseball, football, and 

 bicycle riding. Moderate exer- 

 cise, however, even in infancy, 

 promotes the health of the bones 

 as well as of the other tissues. 



The bones are easily mod i fie d 



in thdr S rOWth ' TkuS the COn ' 



A, tendon of the semi-membranofTs tinued pressure of SOme morbid 

 muscle cut across; , F, tendon deposit, as a tumor Or an en- 

 of same muscle ; C. internal con- , f 



dyle of femur; A posterior crucial lar g ement f an artery, may 

 ligament; E, internal interarticu- cause the absorption Or distor- 



FIG. 28. Section of the Knee 



(Showing ernal structure.) 



cap; A', fatty mass; Z,, anterior One of the Softer tisSUCS. 

 crucial Ugament; M, tendon of 65> Sprains. A twist Or Strain 

 thigh muscles ; P, patella. 



of the ligaments and soft parts 



about a joint is known as a sprain, and may result from 

 a great variety of accidents. When a person falls, the 

 foot is frequently caught under him, and the twist comes 

 upon the ligaments and other structures of the ankle. 



