Geometry of the articular facets of the lateral atlanto-axial joints in the case of occipitalization

This study investigates if atlanto-occipital fusion affects the size and geometrical configuration of the articular facets of the atlanto-axial joint. Morphometric analysis was performed on the male adult skull, the occipital bone of which is assimilated with the first cervical vertebrae (the atlas)...

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Bibliographic Details
Published in:Folia morphologica 2010-08, Vol.69 (3), p.147-153
Main Authors: Ryniewicz, A M, Skrzat, J, Ryniewicz, A, Ryniewicz, W, Walocha, J
Format: Article
Language:English
Subjects:
Adult
Atlanto-Axial Joint - diagnostic imaging
Atlanto-Axial Joint - pathology
Atlanto-Occipital Joint - diagnostic imaging
Atlanto-Occipital Joint - pathology
Biomechanical Phenomena
Cervical Atlas - diagnostic imaging
Cervical Atlas - pathology
Conformation
Fossils
Humans
Image Processing, Computer-Assisted
Male
Morphometry
Occipital bone
Occipital Bone - diagnostic imaging
Occipital Bone - pathology
Ossification, Heterotopic - diagnostic imaging
Ossification, Heterotopic - pathology
Paleopathology
Spine (cervical)
Tomography, X-Ray Computed
Vertebrae
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Summary:This study investigates if atlanto-occipital fusion affects the size and geometrical configuration of the articular facets of the atlanto-axial joint. Morphometric analysis was performed on the male adult skull, the occipital bone of which is assimilated with the first cervical vertebrae (the atlas). The perimeter, Feret's diameter, surface area, and circularity of the inferior articular fa-cets were measured. However, we did not observe significant bilateral differences in size of the inferior articular facets of the assimilated atlas compared to normal first cervical vertebrae. Geometrical conformation of the articular facets of the atlas and axis was assessed using a coordinate measuring machine (PMM - 12106, Leitz). The results obtained from this machine indicated that the inferior articular facets of the assimilated atlas presented asymmetrical orientation compared to the normal anatomy of the atlas. Hence, in the case of occipitalization, the gap between the articulating facets of the atlas and the axis was measured to be greater than in the normal atlanto-axial joint. Computer assisted tomography was applied to visualise the anatomical relationship between the inferior articular facets of the assimilated atlas and the corresponding facets located on the axis. In this case, radiographic examination revealed that the bilaterally articulating facets (inferior and superior) showed disproportion in their adjustment within the lateral atlanto-axial joints. Thus, we concluded that the fusion of the atlas with the occipital bone altered the geometry of the inferior articular facets of the atlas and influenced the orientation of the superior articular facets of the axis.
ISSN:0015-5659