The right vertebral artery arising as a branch of the right internal carotid artery: report of a rare case.

Atypical origins of the vertebral artery (VA) are rare anatomical findings. We present an extremely rare arrangement of the cerebral circulation in a 61-year-old male patient detected on magnetic resonance angiography, where the right VA arose as a direct branch of the cervical internal carotid artery (ICA). This likely reflects the failure of the pro-atlantal artery to regress during the third to fourth week of embryological life. Although the effect of the variant on symptomology is debateable, knowledge of the potential for the VA to arise as a branch of the ICA is pertinent to radiologists and surgeons operating on the great vessels and their branches, particularly vascular surgeons undertaking carotid endarterectomy.