Macroscopic architecture

Two types of internal bone architecture are visible to the naked eye. Cortical bone, the stronger but heavier of the two forms, comprises the outer wall of all bones and fulfils a mainly mechanical function (see insert, Figure 1). It consists of parallel cylinders of matrix (osteons) arranged along the load-bearing axis of the bone.

Within each osteon the matrix is deposited in concentric layers, each 2-3 mm thick, with a predominant fiber direction (like multilayer plywood). The central canal of each osteon contains bone cells, blood vessels and nerves.

Trabecular bone, the second architectural form, is found at the ends of long bones and in the middle of the vertebrae. It consists of a latticework of bony struts, each 100-500 mm thick. Although weaker than cortical bone, it is more cellular and hence more metabolically active.

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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