The arrangement of parallel curved lamellae in the form of tunnels is very common in the body and constitutes the majority of the bone tissue in the diaphyses.
Each of these arrays of lamellae shaped as tunnels is composed of 2 to 15 concentric lamellae. Each lamella measures about 50 micrometers in thickness.
These groupments measure about 0.2–0.4 mm in diameter and a few millimeters long and called Haversian systems or osteons.
The tunnel situated in the center of each Haversian system is the Haversian or osteonal canal.
It contains blood vessels, lymphatic vessels, and nerves.
The osteocytes are located between the lamellae and are nourished by the bony canaliculi that open into the Haversian canal.
The inner surface of the Haversian canal is lined with osteoblasts, as any other bone surface.
Top image
Schematic of a Haversian system formed by three concentric curved lamellae.
Bottom image
The lamellae of the Haversian system are formed by collagen fibers arranged in parallel. Note how the fiber direction differs from one lamella and the next lamella. This arrangement offers great resistance to mechanical pressure and torsion.
