Liquids in a trabecular and a cortical bone play an important mechanical and biological role. Blood supply is an obvious source of low viscosity liquids serving as a transport medium for nutrients and waste products. Other liquids fill the micropores of a compact bone, canaliculi and Haversian systems. Marrow of the cortical and trabecular bone may also be considered as a high viscosity liquid affecting the mechanical behaviour of bone. Collagen and other proteins enclosed in the mineral phase also act like liquids by transmitting hydrostatic pressure and contributing to the viscoelastic behaviour.

The cellular structure with the liquids of a trabecular bone is an excellent energy absorbing material protecting other parts of the body against impact injury. The best examples are the cranium, the pelvis and the ephiphysis of long bones.

When load is applied to a bone, the liquids transmit hydrostatic pressure helping to squeeze the waste products into the blood stream;​ upon removal of the load viscoelastic recovery helps to extract nutrients and oxygen from the blood vessels and transport it towards cells.