osteonen

Osteonen, in Dutch and some other languages often referred to as osteons, are the fundamental structural units of mature compact bone. They are roughly cylindrical and organized around a central blood vessel-containing channel called the Haversian canal. A single osteon comprises concentric lamellae of mineralized bone matrix that surround the canal, creating a laminated, wheel-like structure.

Within the lamellae lie small cavities called lacunae, each housing an osteocyte. The osteocytes are connected to one another through thin cytoplasmic extensions that pass through gap junctions in tiny channels called canaliculi, enabling nutrient exchange and communication throughout the osteon. The outer boundary of each osteon is formed by the endosteum, and the outer surface of the bone is covered by the periosteum. Transverse or oblique channels known as Volkmann’s canals connect neighboring Haversian canals and link the vascular network to the periosteum and the marrow cavity.

Functionally, osteones provide the dense, load-bearing framework of cortical bone. The arrangement of lamellae around the Haversian canal supports resistance to bending and torsion, while the interconnected osteocytes coordinate metabolic activity and remodeling in response to mechanical stimuli. The central canal contains blood vessels and nerves that supply the osteocytes within the osteon.

Formation and remodeling occur through bone remodeling, where osteoblasts create new lamellae to form secondary osteons and osteoclasts resorb old ones. Osteons are characteristic of mature compact bone, particularly in long bones, whereas trabecular (spongy) bone relies on a different arrangement of lamellae within a network of trabeculae.