Circulus arteriosus is formed by: (A) Anterior communicating artery., (B) Basilar artery., (C) Anterior, posterior cerebral and posterior communicating artery., (D) All of the above.
Answer is D. Circulus arteriosus or "circle of Willis" is a anatomical peculiarity of cerebral arteries.
It is formed by
• Anteriorly by anterior communicating artery.
• Posteriorly by basilar artery.
• On each side by anterior cerebral, posterior cerebral, posterior communicating and internal carotid arteries.