Which structure is the Circle of Willis also known as, providing collateral circulation to the brain?

• A. Aorta
• B. Internal Carotid Artery
• C. Basilar Artery
• D. Circle of Willis

Answer: (D)

The Circle of Willis is an arterial ring at the base of the brain that creates collateral circulation by connecting the major blood-supply routes from the internal carotid and vertebrobasilar systems through a network of communicating arteries. This arrangement allows blood to be diverted if one pathway is compromised, helping maintain cerebral perfusion.

This structure is also known as the cerebral arterial circle. Among the given options, the term that matches the same structure is Circle of Willis itself, since the other choices refer to individual arteries or an unrelated trunk rather than the circular arterial arrangement.