In human anatomy, arcuate foramen, also known as ponticulus posticus (Latin for "little posterior bridge") or Kimmerle's anomaly,[1] refers to a bony bridge on the atlas (C1 vertebra) that covers the groove for the vertebral artery. It is a common anatomical variation and estimated to occur in approximately 3-15% of the population.[2][3][4] It occurs in females more commonly than males.[3][5] The ponticulus posticus is created through ossification of the posterior atlantooccipital ligament.
The presence of arcuate foramen is associated with headache, musculoskeletal pain[3] and vertebrobasilar stroke.[2]