The anterior cerebral circulation refers to the internal carotid artery blood supply system, and the posterior cerebral circulation refers to the vertebrobasilar artery blood supply system. 1. Internal carotid artery blood supply system: including the anterior cerebral artery, middle cerebral artery, and anterior choroidal artery, mainly supplying blood flow to the first 3/5 parts of the cerebral hemispheres, including the parietal lobe, frontal lobe, parietal lobe, and basal ganglia area. 2. Vertebrobasilar artery blood supply system: including vertebral artery, basilar artery, posterior cerebral artery. It mainly supplies blood flow to the posterior 2/5 part of the cerebral hemispheres, including the midbrain, pons, medulla oblongata, cerebellum, posterior part of the cerebral hemispheres, and part of the mesencephalon. Clinically, according to the distribution of blood supply to the anterior and posterior circulation of the brain, it provides great help in the treatment of infarction as well as hemorrhage in different parts of the brain.