Vol 69, No 3 (2010)
Original article
Published online: 2010-08-02
Geometry of the articular facets of the lateral atlanto-axial joints in the case of occipitalization
Folia Morphol 2010;69(3):147-153.
Abstract
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.
(Folia Morphol 2010; 69, 3: 147-153)
(Folia Morphol 2010; 69, 3: 147-153)
Keywords: occipitalizationatlascervical vertebraecraniovertebral joint