Arcuate Foramen

The arcuate foramen is formed by a bony bridge (ponticulus posticus, or little posterior bridge) over a groove in the posterolateral margin of C1 known as the sulcus arteriae vertebralis. The vertebral artery and first cervical nerve normally travel within the sulcus arteriae vertebralis, and, when the ponticulus posticus is present, through the arcuate foramen.

The arcuate foramen is also known as as Kimmerle anomaly, foramen sagittale, foramen atlantoideum, foramen retroarticulare superior, and canalis vertebralis. It has been suggested that the ponticulus posticus comes about through ossification of the oblique portion of the atlantooccipital ligament, while others have found no age-difference to suggest an acquired process.

References

• Huang MJ, Glaser JA. Complete arcuate foramen precluding C1 lateral mass screw fixation in a patient with rheumatoid arthritis: case report. Iowa Orthop J. 2003;23:96-9.
• Krishnamurthy A, Nayak SR, Khan S, Prabhu LV, Ramanathan LA, Ganesh Kumar C, Prasad Sinha A. Arcuate foramen of atlas: incidence, phylogenetic and clinical significance. Rom J Morphol Embryol. 2007;48(3):263-6.
• Stubbs DM. The arcuate foramen. Variability in distribution related to race and sex. Spine (Phila Pa 1976). 1992 Dec;17(12):1502-4.