Cortical (Compact) Bone
Definition
The dense outer shell of long bones and the tables of flat bones. Approximately 80% of skeletal mass. High mineral density (65-70% hydroxyapatite by dry weight) makes it mechanically stiff and taphonomically persistent. Primary site of forensic histological analysis.
- Location
- Outer shell of long bones and flat-bone tables
- Share of skeletal mass
- About 80 percent
- Mineral content
- 65-70% hydroxyapatite by dry weight
- Property
- Mechanically stiff, taphonomically persistent
Common questions
Why does high mineral content make cortical bone taphonomically persistent?+
The dense hydroxyapatite matrix resists chemical breakdown and physical crushing better than less mineralised tissue, so cortical bone tends to survive burial, weathering, and time far longer than cancellous bone or soft tissue.
How does the 80 percent mass figure relate to cancellous bone's role in the skeleton?+
Cancellous bone makes up the remaining roughly 20 percent by mass but occupies proportionally more surface area at joint ends, so mass share alone understates its metabolic and biomechanical role even though cortical bone dominates by weight.
Related terms
- Epiphyseal Growth Plate (Physis)
- The cartilaginous zone between the epiphysis and metaphysis where endochondral ossification occurs during growth. Closes (fuses) at puberty under the influence of...
- Haversian System (Secondary Osteon)
- The basic structural unit of mature cortical bone: a cylinder of 4-20 concentric lamellar rings around a central Haversian canal carrying blood...
- Interstitial Lamellae
- The angular remnants of older osteons left behind after a BMU has partially resorbed them. Their relative area decreases with age as...
- Kerley Method
- A histological age estimation method published by Ellis Kerley in 1965, based on counting secondary osteons, osteon fragments, circumferential lamellar bone, and...
- Lacuna
- A small lens-shaped cavity within bone lamellae that houses an osteocyte cell body. Lacunae are connected by canaliculi radiating toward the Haversian...
- Osteoclast
- The large, multinucleated bone-resorbing cell responsible for excavating the resorption tunnel in a BMU. Activated by the RANKL/OPG cytokine axis. Creates the...
- 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...
- Trabecular (Cancellous) Bone
- The porous, lattice-like interior bone occupying epiphyses, metaphyses, and flat bones. High surface area and metabolic activity but rapidly lost in taphonomic...
- Wolff's Law
- The principle that bone is deposited and resorbed in response to mechanical loading history. Cortical thickness and trabecular orientation follow principal stress...