Haversian canal

one of numerous small channels or cylindrical tubes that run through compact BONE (the outer layer of bones) and contain BLOOD VESSELS and NERVES . They form part of the Haversian system, consisting of the canals surrounded by concentric, alternate layers of bone lamellae (thin plates) and lacunae (spaces) that house bone CELLS . These form cylindrical units in the compact bone and the lacunae are linked up by minute channels called canaliculi.