The anterior and posterior cerebral arteries are both branches of the internal carotid artery

Majority: Middle cerebral artery

Superior inch: Anterior cerebral artery

1. L ventricle
2. Ascending aorta
3. Aortic Arch
4. Brachiocephalic trunk
5. R Common Carotid artery
6. R Internal Carotid artery
7. R anterior cerebral artery

It connects left and right anterior cerebral arteries

I beileve (Looking in my Hole's anatomy & physiology text) that the anterior cerebral branches off the middle cerebral, which branches from the posterior communicating artery. Or it circles around to the anterior communicating artery. They all form the cerebral arterial circle.