The diagram above shows a transverse view of an osteon (Haversian system) - the basic unit of compact bone.
The diagram above shows a longitudinal view of an osteon.
Some, mostly older, compact bone is remodelled to form these Haversian systems (or osteons). The osteocytes sit in their lacunae in concentric rings around a central Haversian canal (which runs longitudinally). The osteocytes are arranged in concentric rings of bone matrix called lamellae (little plates), and their processes run in interconnecting canaliculi. The central Haversian canal, and horizontal canals (perforating/Volkmann’s) canals contain blood vessels and nerves from the periosteum.