Abstract
INTRODUCTION
The paired vertebral arteries (VA), left and right, are major blood vessels within the neck that supply the brain with oxygenated blood. They originate from the left and right subclavian arteries and ascend through the left and right transverse foramina (TF) from the level of the sixth cervical vertebra to the first cervical vertebra.
The arcuate foramen (AF) is an anatomical variation of the posterior portion of the atlas, occurring unilaterally or bilaterally. It consists of ossification of the posterior atlanto-occipital membrane around the VA as it begins to ascend towards the brain to form a bony arch-like structure.
AIM
The primary aim of the study was to examine dried, cadaveric human atlases for the concomitant size relationship between the two named foramina observed in the atlas vertebrae (C1), namely the transverse foramen (TF) and the anomalous arcuate foramen (AF). The secondary aims of this study were to examine the size relationships of the AF to the Ipsilateral and contralateral TF, and lastly, to compare the size of the TF in the presence or absence of an AF.
METHODOLOGY
This explorative study used a primary quantitative correlation analysis of dried cadaveric human atlases to investigate the size-relationship between the TF and the AF. Additionally, the morphology of the TF was described according to Taitz et al. (1978) classification. This study collected 120 atlases (60 atlases containing an AF and 60 atlases with an AF absent) to be analysed. Linear and surface area measurements were completed for each foramen. The 60 atlases with the AF absent made up the control cohort which was split into 30 Females and 30 Males. The 60 atlases with the AF present was not an equal split between males and females. The data was collected from the Raymond A. Dart Collection of Modern Human Skeletons housed in the School of Anatomical Sciences, Health Science Campus, University of the Witwatersrand, Johannesburg. The data was captured using Microsoft® Excel® spreadsheets. Statistical analyses were conducted using IBM® SPSS version 27.
RESULTS
The results obtained from this study revealed that the AF’s surface area on the left side was greater in size when compared to the contralateral TF surface area. On the right side, however, the opposite is true: the
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AF’s surface area was greater than the TF surface area on the ipsilateral side but not the contralateral TF. When comparing the effect of the presence of the AF on the TF, it was found that the TF with the AF present were greater in size when compared to the TF in the absence of an AF.
CONCLUSION
The overall findings of this study have added to the body of knowledge and will help inform clinicians and anatomists about the size-relationship between the AF and TF. Additionally, results from this study may inform clinicians about possible clinical implications of the narrowing of either foramen, especially in the setting of upper neck manipulations. This could have implications for specific chiropractic and surgical techniques employed on patients.