ANATOMY, 



DESCRIPTIVE AND SURGICAL, 



Osteology. 



IN the construction of the human body, it would appear essential, in the first 

 place, to provide some dense and solid texture capable of forming a framework 

 for the support and attachment of the softer parts of the frame, and of forming 

 cavities for the protection of the more important vital organs; and such a 

 structure we find provided in the various bones, which form what is called the 

 Skeleton (sx^xxw, to dry up). 



Structure and Physical Properties of Bone. Bone is one of the hardest structures 

 of the animal body ; it possesses also a certain degree of toughness and elasticity. 

 Its color, in a fresh state, is of a pinkish-white externally, and deep red within. 

 On examining a section of any bone, it is seen to be composed of two kinds 

 of tissue, one of which is dense and compact in texture, like ivory; the other 

 consisting of slender fibres and lamellae, which join to form a reticular structure; 

 this, from its resemblance to lattice-work, is called cancellated. The compact 

 tissue is always placed on the exterior of a bone; the cancellous tissue is always 

 internal. The relative quantity of these two kinds of tissue varies in different 

 bones, and in different parts of the same bone, as strength or lightness is requisite. 

 Close examination of the compact tissue shows it to be extremely porous, so that 

 the difference in structure between it and the cancellous tissue depends merely 

 upon the different amount of solid matter, and the size and number of the spaces 

 in each; in the compact tissue the cavities being small, and the solid matter 

 between them abundant, whilst in the cancellous tissue the spaces are large, and 

 the solid matter diminished in quantity. 



Chemical Analysis. Bone consists of an organic or animal, and an inorganic 

 or earthy material, intimately combined together: the animal matter giving to 

 bone its elasticity and toughness, the earthy part its hardness and solidity. The 

 animal constituent may be separated from the earthy by steeping bone in a dilute 

 solution of nitric or muriatic acid : by this process the earthy constituents are 

 gradually dissolved out, leaving a tough semi-transparent substance, which retains, 

 in every respect, the original form of the bone. This is often called cartilage, 

 but differs from it in being softer, more flexible, and, when boiled under a high 

 pressure, it is almost entirely resolved into gelatine. Cartilage docs, however, 

 form the animal basis of bone in certain parts of the skeleton. Thus, according 

 to Tomes aud De Morgan, it occurs in the petrous part of the temporal bone; and, 

 according to Dr. Sharpey, on the articular ends of adult bones, lying underneath 

 the natural cartilage of the joint. The earthy constituent may be obtained by 

 subjecting a bone to strong heat in an open fire with free access of air. By these 

 means the animal matter is entirely consumed, the earthy part remaining as a 

 white brittle substance still preserving the original shape of the bone. Both 

 constituents present the singular property of remaining unaltered in chemical 

 composition after a lapse of centuries. 

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