Final answer:
The middle cerebral artery supplies blood to the temporal and parietal lobes of the cerebrum. If there were a blockage just posterior to the middle cerebral artery on the left, the blood would come from the posterior communicating artery on the left side of the brain.
Step-by-step explanation:
The middle cerebral artery is responsible for supplying blood to the temporal and parietal lobes of the cerebrum in the brain. It is one of the branches of the internal carotid artery. If there were a blockage just posterior to the middle cerebral artery on the left, the blood would come from the posterior communicating artery on the left side of the brain.