HYGIENE OF THE SKELETON 249 



heads and shafts being separated by a cartilagenous area 

 which does not solidify until late in life. On this account 

 bones of the young are especially subject to distortion 

 from pressure which, if continued, may result in permanent 

 change of shape or deformity. Another factor which makes 

 young bones sensitive to pressure is the small proportion 

 of lime in them. Bow legs, for example, are a result of 

 allowing children to walk too soon, and thus subjecting the 

 bones to the weight of the body before they are sufficiently 

 stiffened to resist this pressure. Sitting for long periods 

 at a bench in schoolroom when the bench is too high to 

 allow the feet to touch the floor may permanently bend 

 the thigh bones. A still more common deformity is what 

 is known as round shoulders. The bending of the body 

 over books at school, or crouching attitudes in writing, 

 helps to increase the natural curvature of the spine and 

 produce this unsightly deformity. 



The ease with which bones may be molded is illustrated 

 in the practice of dentists in applying pressure to the jaw- 

 bones to straighten teeth. Braces, to remedy round shoul- 

 ders, are examples of this same plasticity of bone to external 

 pressure. 



One of the worst cases of deformity from pressure is 

 found in the tight lacing of corsets as practiced by many 

 women. As a result, the ribs are bent and the decrease 

 in the size of the waist is accompanied by crowding of the 

 chest and abdominal regions to such an extent as to hinder 

 the action of the inclosed organs. 



Still another effect of pressure applied to joints is injury 

 to the tissues and ligaments which result in the formation 

 of painful swellings, called bunions. Tight shoes are often 

 responsible for these painful deformities. 



