Traumatic [[vertebral artery dissection]]s tend to occur where the [[vertebral artery]] crosses bony prominences, e.g. at the [[atlantoaxial junction]] or where it enters the [[foramen transversarium]] (usually at [[C6]]). Spontaneous dissections tend to be intracranial and commonly occur on the dominant VA. Unlike cervical ICA dissections, which tend not to propagate intracranially through the carotid canal, high cervical VA dissections can readily propagate intracranially through the [[foramen magnum]].