Diagram of compact bone from a transverse section of a typical long bone's cortex.
Diagram of a typical long bone showing both compact (cortical) and cancellous (spongy) bone.
Haversian canals[note 1] (sometimes canals of Havers, named after BritishphysicianClopton Havers) 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.
In mature compact bone most of the individual lamellae form concentric rings around larger longitudinal canals (approx. 50 µm in diameter) within the bone tissue. These canals are called haversian canals. Haversian canals typically run parallel to the surface and along the long axis of the bone. The canals and the surrounding lamellae (8-15) are called a haversian system or an osteon. A haversian canal generally contains one or two capillaries and nerve fibres.