Retrotransverse foramen of the atlas: prevalence and bony variations.
Juan Alberto Sanchis-GimenoEsther Blanco-PerezMarcelino Perez-BermejoSusanna LlidoShahed NallaPublished in: European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society (2017)
The RTF is a nonmetric variant of the atlas vertebra that can present non-degenerative and non-traumatic spiculae or it can be unclosed. In addition, it can be associated with the presence of unclosed transverse foramina.