A case of occipital artery originating from the vertebral artery.

Anomalies of the vertebral artery (VA) and its branches are rare but critical in neurovascular procedures. In a 38-year-old female, digital subtraction angiography revealed an anomalous origin of the occipital artery (OA) from the V3 segment of the left VA, with a tortuous course supplying the neck and scalp. Below the OA's origin, the suboccipital artery of Salmon arose, bifurcating into two branches. Additionally, an extradural posterior inferior cerebellar artery originated from the same segment, entering the skull via the foramen magnum and dividing into medial and lateral trunks. This unique coexistence of vascular variants highlights the need for detailed preoperative vascular outlining to minimize intraoperative risks.