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If we divide any of the long bones longitudinally, we find two kinds of structure, the hard or compact, and the alveolar or spongy. Indeed there is no bone that does not exhibit to some extend both of these structures; the compact forming its external, and the spongy its internal part. These two formations are clearly seen in the bones which compose the skull, as in the following cut, with the spongy or cancellated structure between them. This serves to illustrate the structure of all of the flat bones.

Bone Structure

If we divide any of the long bones longitudinally, we find two kinds of structure, the hard or compact,…