This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Which of the following is not considered a part of Circle of Willis? 
Select and explain. 
A. Anterior cerebral artery, B. Middle cerebral artery, C. Posterior communicating artery, D. Posterior cerebral artery
B: Middle cerebral artery
Answer: B: Middle cerebral artery 
Explanation: Circle of Willi's is formed by:-

In front: anterior communicating artery.
Anterolaterally: two anterior cerebral artery.
Laterally: proximal segments of both internal carotid arteries.
Postero-laterally: two posterior communicating arteries.
Behind: proximal segments of both posterior cerebral arteries, arising at bifurcating terminal of the basilar artery.