Haversian canals are a series of tubes around narrow channels formed by lamellae. This is the region of bone called compact bone. Osteons are arranged in parallel to the long axis of the bone. The Haversian canals surround blood vessels and nerve cells throughout the bone and communicate with osteocytes in lacunae (spaces within the dense bone matrix that contain the living bone cells) through canaliculi. This unique arrangement is conducive to mineral salt deposits and storage which gives bone tissue its strength. [ http://en.wikipedia.org/wiki/Haversian_canal ]