Which artery is a single short shunt connecting the left and right anterior cerebral arteries?

• A. MCA
• B. Anterior Communicating Artery
• C. Posterior Communicating Artery
• D. Internal Carotid Artery

Answer: (B)

Think about how the brain’s arteries connect in the circle of Willis. The two anterior cerebral arteries run along the midsagittal surface toward the frontal lobes, and they are joined by a small, short vessel that acts as a bridge between them—the anterior communicating artery. This single short shunt provides a cross-flow link between the left and right ACAs, completing the circle and enabling collateral circulation if one side is compromised.

Other vessels have different roles: the middle cerebral artery supplies the lateral aspects of the hemispheres, the posterior communicating artery connects the internal carotid system to the posterior circulation rather than linking the two ACAs, and the internal carotid artery is a major feeding trunk rather than a bridge between the two anterior cerebral arteries.