Osteon
Definition
The basic structural unit of cortical bone: a set of concentric lamellae surrounding a central Haversian canal. Human secondary osteons are roughly circular, 200-300 µm in mean diameter. Osteon morphology (shape, size, population density) is used for both human-vs-non-human discrimination and histological age estimation.
- Also called
- Haversian system
- Structure
- Concentric lamellae around a central Haversian canal
- Human diameter
- Roughly 200 to 300 µm mean diameter, circular
- Forensic uses
- Human-vs-nonhuman discrimination, histological age estimation
Common questions
How does osteon shape distinguish human from animal bone?+
Human secondary osteons are relatively uniform and circular, while many non-human mammals show plexiform or laminar bone with a more organised, non-Haversian pattern, though some large mammals do develop Haversian bone that can complicate the distinction.
Why does osteon population density change with age?+
Bone continually remodels throughout life, and each remodeling cycle overlays new osteons on older ones; because this accumulates over time, counting intact and fragmentary osteons per unit area in a cortical cross-section gives a histological age estimate.
Related terms
- Cortical Index
- The ratio of total cortical bone area to total bone cross-sectional area at a defined midshaft location. Used in fragment identification to...
- Fragment Identification
- The assignment of a bone fragment to a specific skeletal element (rib, long-bone shaft, vertebral arch, cranial vault, etc.) and anatomical region,...
- Haversian Canal
- The central vascular channel of an osteon, carrying blood vessels and nerves through the cortical bone. Diameter 20-70 µm in human bone....
- Minimum Number of Individuals (MNI)
- The smallest number of distinct individuals required to account for all skeletal elements present in an assemblage. Determined by identifying the element...
- Neural Arch
- The posterior bony arch of a vertebra, formed by two pedicles and two laminae meeting at the spinous process. In foetal and...
- Owsley-Mann Protocol
- The fragment identification and triage methodology developed by Douglas Owsley (Smithsonian Institution) and Robert Mann (DPAA) for systematically assigning commingled bone fragments...
- Plexiform Bone
- A microstructural pattern found in the cortical bone of large rapid-growth mammals (bovids, horses, deer) characterised by alternating layers of woven bone...
- Side Determination
- The osteological process of assigning a paired skeletal element (clavicle, humerus, femur, rib, os coxae, etc.) to the left or right side...
- Species Confirmation (DNA)
- PCR-based or sequencing-based confirmation that a bone fragment is of human (Homo sapiens) origin, using human-specific primer sequences or mitochondrial cytochrome b...