Unusual origin of the left vertebral artery

The vertebral artery is important to posterior cerebral circulation. Several researchers have reported anomalous origins of the vertebral artery such as from the aortic arch, between the left common carotid artery and left subclavian artery or after left subclavian artery, from the thyrocervical trunk, from the brachiocephalic trunk, from the common carotid artery, from the external carotid artery, from a common carotid trunk formed by left subclavian artery and left vertebral artery. We encountered a variation of the aortic arch gave off four branches, brachiocephalic trunk, left common carotid artery, left vertebral artery, left subclavian artery. The left vertebral artery originated from the aortic arch between the origins of the left common carotid artery and the left subclavian artery. The origin distances between the left vertebral artery and the arteries were 3.96 mm and 5.10 mm, respectively. Diameter of the left vertebral artery at its origin was 5.51 mm. The left vertebral artery coursed upward to the transvers foramen of the C6. The length of the prevertebral segment of the left vertebral artery was 88.5 mm. The anatomic and morphologic variations of the left vertebral artery are significant for diagnostic and surgical procedures in the head and neck region. It is of clinical importance to know the origin and course of prevertebral segment of the vertebral artery in detail and being aware of the possible variations.