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Results for “Axis, Cervical Vertebra”

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At least 19 recordsLinked to original sources
PubMed1995

Hox genes and the evolution of vertebrate axial morphology.

A common form of evolutionary variation between vertebrate taxa is the different numbers of segments that contribute to various regions of the anterior-posterior axis; cervical vertebrae, thoracic vertebrae, etc. The term 'transposition' is used to describe this phenomenon. Genetic experiments with homeotic genes in mice have demonstrated that Hox genes are in part responsible for the specification of segmental identity along the anterior-posterior axis, and it has been proposed that an axial Hox code determines the morphology of individual vertebrae (Kessel, M. and Gruss, P. (1990) Science 249, 347-379). This paper presents a comparative study of the developmental patterns of homeobox gene expression and developmental morphology between animals that have homologous regulatory genes but different morphologies. The axial expression boundaries of 23 Hox genes were examined in the paraxial mesoderm of chick, and 16 in mouse embryos by in situ hybridization and immunolocalization techniques. Hox gene anterior expression boundaries were found to be transposed in concert with morphological boundaries. This data contributes a mechanistic level to the assumed homology of these regions in vertebrates. The recognition of mechanistic homology supports the historical homology of basic patterning mechanisms between all organisms that share these genes.

Animals↗
PubMed1985

[Nontraumatic spondylolysis of the axis vertebra].

A case of nontraumatic spondylolysis of the axis vertebra is presented. A 55-year-old man suddenly experienced nausea and dizziness on January 15, 1984 when he rotated his neck toward the left. Since this episode, he experienced the same attacks twice. On examination, the patient was afraid of moving his neck abruptly and on gradual hyperextension of his neck, he started to complain of slight dizziness. But otherwise no abnormalities of motor, sensory and cerebellar functions were noticed. Lateral view of plain films of the cervical spine revealed a bilateral bony defect in the lamina of the axis vertebra. The surface of the bony margin around the defect seemed to be well corticated and smooth. There was no spondylolisthesis between the second and the third cervical vertebra. CT scan of the axis vertebra also showed bilateral true bony defect, not in the pars interarticularis but in the inferior articular process of the axis vertebra. Spondylolysis with or without spondylolisthesis of the cervical vertebrae is relatively rare and about 48 cases of the cervical spondylolysis have been reported in the previously published literature.

Axis, Cervical Vertebra↗
PubMedDate not supplied

Narrow axis: an inherited anomaly of the second cervical vertebra in the rabbit.

Narrow axis, an inherited anomaly resulting in a marked narrowing of the second cervical vertebra, has been observed in strain X/J rabbits. This condition is first recognizable on X rays at 32-33 days gestation. For size comparisons 21 measurements of the first five cervical vertebrae were taken on the skeletons of each of 14 strain X/J animals (7 normal and 7 with narrow axis) and 14 IIIC/J animals for control at two months of age and 27 strain X/J (11 normal and 16 narrow axis) and 14 strain IIIC/J at seven months of age. The primary effect appeared to be a premature fusion of the centrum with its neural arches. Expression is variable. The effect on the posterior articulation of the atlas appeared to be secondary and adaptive. The other cervical vertebrae and the foramen magnum were relatively unaffected. In the 20-year period encompassed in this report, X rays of 3244 rabbits were used for genetic analysis. Inheritance appears to be due to a single autosomal recessive gene with incomplete penetrance. The condition is neither sex-linked nor sex-limited. We propose the symbol nx for the gene responsible for narrow axis in the rabbit.

Animals↗
PubMedDate not supplied

Isolated congenital cervical block vertebrae below the axis with neurological symptoms.

A reviews of 13 cases of symptomatic isolated congenital cervical fusion (block vertebrae) below the C2 level is presented. Ten cases were collected from a review of the English literature and three new cases were added. All 13 patients presented neurologic symptoms of radiculopathy and/or myelopathy with either no history of trauma or only minor trauma. Pathogenesis of symptoms is due to degenerative arthritis of the adjacent mobile segments, spinal stenosis, and subluxation of the adjacent mobile segments. The significance of coexisting spinal stenosis and segmental instability is emphasized and is related to the symptoms and treatment of the condition. Symptomatic patients can be treated satisfactorily with adequate decompressive laminectomy and fusion of the unstable segments.

Adult↗
PubMed1976

[Fractures of the dens of the 2d cervical vertebra and their treatment].

Fractures of the dens axis make 10-15 per cent to all injuries of the cervical portion of the vertebral column. The potential danger of these injuries and difficulties of their treatment are conditioned by anatomo-functional features of this portion of the spine. The mechanism of fractures of the dens axis is not clear yet. Clinical manifestations of dens axis fractures are determined by the character and extent of its desplacement. Its diagnosis is somewhat difficult sometimes. Conservative therapy is not always a success. The existing methods of surgical treatment of dens axis fractures make it possible to gain the cure nearly in all cases.

Axis, Cervical Vertebra↗