Bilateral vertebral arteries entering the C4 foramen transversarium with the left vertebral artery originating from the aortic arch

Vertebral arteries (VAs) serve as major blood vessels to the central nervous system. VAs typically arise from the subclavian arteries and ascend separately within the transverse foramina of the cervical vertebrae (C6-C1) before entering the skull at the foramen magnum and joining at the base of the pons to form the basilar artery of the vertebrobasilar circulation. Therefore, variations in the origin and anatomic course of the VAs have implications for invasive medical procedures involving the superior thoracic/cervical regions or the cervical vertebrae. The current case report describes variation in the entry point of both VAs and the site of origin of the left vertebral artery. The variation was revealed during routine dissection of a 72-year-old female cadaver. It was found that the left vertebral artery originated directly from the aortic arch to abnormally enter the transverse foramen of C4 instead of the transverse foramen of C6. The right vertebral artery arose as usual from the right subclavian artery. However, the right vertebral artery also directly entered the transverse foramen of C4 instead of the transverse foramen of C6.