what does the vertebral artery supply
The vertebral and basilar arteries supply blood to several structures in the brain including: the occipital cortex, the brainstem consisting of the midbrain, pons and medulla, the cerebellum and the thalamus. Atherosclerosis or hardening of the arteries is the primary cause of vertebrobasilar disease. The narrowing of the vertebral or basilar arteries caused by atherosclerosis creates vertebrobasilar insufficiency (VBI), or an insufficient delivery of blood flow to the posterior structures of the brain.