Anatomic and Radiologic Appearance of Several Variants of the Craniocervical Junction

University Hospital RWTH Aachen, Aachen, North Rhine-Westphalia, Germany
Skull Base 02/1996; 6(2):83-94. DOI: 10.1055/s-2008-1058649
Source: PubMed
Four typical manifestations of the occipital vertebra are described from both an anatomic and a radiologic point of view; the basilar process, the condylus tertius, the paracondylar process, and the isolated prebasioccipital arch. The clinical importance of the described variants is discussed.

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    • "If it gets separated from the occipital bone and presents as an isolated conical bony mass, it is termed as 'massa paracondylica'. If this massa paracondylica fuses with the transverse process of atlas, it is called as 'processus epitransversus' (Prescher 1996; Rao 2002). The process is present close to the insertion of the lateral rectus capitis muscle. "
    [Show description] [Hide description] DESCRIPTION: Background: magnum, either in the midline proatlas is derived from the fourth occipital sclerotome. There is a broad spectrum of occipital vertebrae variations which include paracondylar process and These manifestations during first and second decades of life. Materials and Method: Department of A presence of remnants of occipital vertebrae. Results: Out of 200 skulls, 4 skulls showed remnants of occipital vertebrae (2%). Median occipital condyle was observed in one skull (0.5%), hypocondylar arch was bilateral basilar Conclusion: during interpretation diagnosis of its diseases and the neurosurgeons while doing skull base surgeries. An attempt has been made in the present study to throw light on the various manifestations of occ embryological and clinical significance.
    Full-text · Research · Apr 2016
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    • "It has a prevalence of between 0.5% and 5% in modern humans and is in the great majority of cases symptomless (Friedlowsky 1869; Hanihara and Ishida 2001). The condylus tertius results from an embryologic persistence of the hypochondral arch of the cranial half of the 6th somite that forms the proatlas and is normal in reptiles (Meckel 1815; Prescher et al. 1996; von L├╝dinghausen et al. 2002). It has to be differentiated from other developmental anomalies of the craniovertebral junction, including the ossiculum terminale and the os odontoideum. "
    [Show abstract] [Hide abstract] ABSTRACT: The Nariokotome boy skeleton KNM-WT 15000 is the most complete Homo erectus fossil and therefore is key for understanding human evolution. Nevertheless, since Latimer and Ohman (2001) reported on severe congenital pathology in KNM-WT 15000, it is questionable whether this skeleton can still be used as reference for Homo erectus skeletal biology. The asserted pathologies include platyspondylic and diminutive vertebrae implying a disproportionately short stature; spina bifida; condylus tertius; spinal stenosis; and scoliosis. Based on this symptom complex, the differential diagnosis of spondyloepiphyseal dysplasia tarda, an extremely rare form of skeletal dysplasia, has been proposed. Yet, our reanalysis of these pathologies shows that the shape of the KNM-WT 15000 vertebrae matches that of normal modern human adolescents. The vertebrae are not abnormally flat, show no endplate irregularities, and thus are not platyspondylic. As this is the hallmark of spondyloepiphyseal dysplasia tarda and related forms of skeletal dysplasia, the absence of platyspondyly refutes axial dysplasia and disproportionate dwarfism. Furthermore, we neither found evidence for spina bifida occulta nor manifesta, whereas the condylus tertius, a developmental anomaly of the cranial base, is not related to skeletal dysplasias. Other fossils indicate that the relatively small size of the vertebrae and the narrow spinal canal are characteristics of early hominins rather than congenital pathologies. Except for the recently described signs of traumatic lumbar disc herniation, the Nariokotome boy fossil therefore seems to belong to a normal Homo erectus youth without pathologies of the axial skeleton. Am J Phys Anthropol, 2013. ┬ę 2013 Wiley Periodicals, Inc.
    Full-text · Article · Mar 2013 · American Journal of Physical Anthropology
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    • "The third atlanto-occipital joint, if present, may disrupt the biomechanics between the occiput and the atlas resulting in mechanical pain and increased rigidity. The condition may also be associated with an osseous torticolis [28]. The head may adopt an attitude of flexion termed caput obstipum [29]. "
    [Show abstract] [Hide abstract] ABSTRACT: Minor variations in the ossicles, foramina and ridges of the cranium have aroused the curiosity of anatomists for many decades. These non-metric variants help us to study the genetic relationships among ancient populations. Since these traits show considerable frequency differences in different populations, they can be used as anthropological characters in epidemiological studies. These variants indirectly reflect the part of underlying genotype of a given population thus implying their usefulness in biological comparisons of related groups. They can be used for the assessment of the existence of the parental structures within a community or as taxonomic indicators. For anthropological studies, the traits should be genetically determined, vary in frequency between different populations and should not show age, sex, and side dependency. The present study was conducted on hundred dry adult human skulls from Northern India. They were sexed and studied for the presence of hyperostotic traits (double hypoglossal canal, jugular foramen bridging, and paracondylar process). Sexual and side dimorphism was observed. None of the traits had shown statistically significant side and sexual dimorphism. Since the dimorphism is exhibited by none of them, it can be postulated that these traits are predominantly under genetic control and can be effectively used for population studies.
    Full-text · Article · Dec 2012 · Anatomy & cell biology
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