title: The median atlanto-occipital joint in advanced age.
abstract: METHODS
  Exploration of the craniocervical junction in cadavers of elderly individuals.
  
  
  OBJECTIVE
  Histologic evaluation of osseous contact zones observed between the basiocciput and anterior arch of the atlas.
  
  
  BACKGROUND
  Previous findings of possible osseous contact zones at the anterior rim of the foramen magnum and anterior arch of the atlas suggested the existence of real joints.
  
  
  METHODS
  A total of 100 cadaver specimens were investigated using magnetic resonance imaging, computerized tomography, and median saw-cut and histologic sections.
  
  
  RESULTS
  Of the specimens, 42% showed osteoarthritis-related osteophytes (primarily directed cranially) of the articular surfaces of the median atlantoaxial joint. In 5 cases, a large osteophyte of the anterior arch of the atlas touched the basiocciput. In 3 cases, a third occipital condyle touched the anterior arch of the atlas and/or tip of the dens. These osseous contact zones were histologically verified as real joints (the median atlanto-occipital or occipito-odontoid joints).
  
  
  CONCLUSIONS
  Of the 8 median atlanto-occipital joints found in this study, 3 were third occipital-condyle based, and 5 osteoarthritis-based. The former were congenital in character, while the latter were acquired.
authors.affiliation: Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany. anat033@mail.uni-wuerzburg.de
authors.forename: Michael
authors.initials: M
authors.lastname: Von Lüdinghausen
authors.forename: Andreas
authors.initials: A
authors.lastname: Prescher
authors.forename: Ikuo
authors.initials: I
authors.lastname: Kageya
authors.forename: Ken
authors.initials: K
authors.lastname: Yoshimura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001269:Atlanto-Occipital Joint / Q000002:abnormalities* / Q000033:anatomy & histology* / Q000473:pathology; D002102:Cadaver; D000013:Congenital Abnormalities / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis / Q000473:pathology*; D014057:Tomography, X-Ray Computed