View source for Osteon

{{Infobox Anatomy |
  Name         = Osteon |
  Latin        = |
  GraySubject  = 18 |
  GrayPage     = 89 |
  Image        = Illu compact spongy bone.jpg |
  Caption      = |
  Image2       = Gray77.png |
  Caption2     = Transverse section of body of human fibula, decalcified. X 250.  |
  Width        = 350 | 
  System       = |
  MeshName     = |
  MeshNumber   = |
  DorlandsPre  = o_08 |
  DorlandsSuf  = 12601039  |
}}


==Overview==
'''Osteons''' (also called '''Haversian system''' in honor of [[Clopton Havers]]) are predominant structures found in some lamellar or [[compact bone]]. Osteons are  found in many of the bones of many mammals, birds, reptiles, and amphibians running in a meandering way but generally parallel to the long axis of bones. It is this section of [[compact bone]] that is called matrix. 

In the center of the osteon is a '''central canal''', called the [[Haversian canal]]. 

The central canal is surrounded by concentric layers of matrix called '''lamellae'''.  These lamellae are laid down one after the other over time, each successive one inside the preceding one. [[Collagen]] fibers in a lamella run parallel to each other but the orientation of collagen fibers across separate lamellae is oblique. The fiber density is also lower at the border between adjacent lamellae, which accounts for the distinctive appearance of an osteon. 

[[Osteocyte]]s are found between concentric lamellae and connected to each other and the central canal by [[cytoplasm|cytoplasmic]] processes through the canals called '''[[canaliculi]]'''. This network permits the exchange of [[nutrient]]s and [[metabolism|metabolic]] waste. 

Osteons are separated from each other by '''cement lines'''. [[Collagen]] fibers and canaliculi do not cross cement lines. 

The space between separate osteons is occupied by '''interstitial lamellae''', which were formed by pre-existing osteons that have since been reabsorbed. 

Osteons are connected to each other and the [[periosteum]] by oblique channels called [[Volkmann's canals]].

==Use in archaeology and forensics==

Osteons carry their history so that given the right conditions they can be used to "read" the sex, age, health history, motor history and apparently something of the diet of an individual's bone. Osteons and their arrangement also vary according to  taxon, so that genus and sometimes species can be differentiated using a bone fragment not otherwise identifiable.  This is of use in archaeology, paleontology and forensics.

==See also==
* [[Haversian canals]]


==Literature==
* Martiniaková, Monika  2006  ''Differences in Bone Microstructure of Mammalian Skeletons''.  Faculty of Natural Sciences, Constantine the Philosopher University in Nitra:  Nitra, Slovakia.
* Pfeiffer, Susan; Crowder, Christian; Harrington, Lesley; and Brown, Brown 2006  "Secondary Osteon and Haversian Canal Dimensions as Behavioral Indicators," ''American Journal of Physical Anthropology'', 131 (4): 460 - 468. 
* Cooper, Reginald R.; Milgram, James W.; and Robinson, Robert A. 1966 "Morphology of the Osteon:  An Electron Microscopic Study," ''Journal of Bone and Joint Surgery,'' 48:1239-1271.

==External links==
* SLIBS Bone Website:  http://www.trinity.edu/rblyston/bone/intro2.htm
* {{MeshName|Haversian+System}}
* {{BiowebUW|zoolab/Table_of_Contents/Lab-1b/Bone_Model/bone_model.htm|Bone model}}

{{Bone and cartilage}}

[[Category:Skeletal system]]


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