Anatomical Variations in Circle of Willis in Patients Undergoing Magnetic Resonance Angiography

Dr. Siddhi Doshi, Dr. Ganesh Avhad

Abstract: The circle of Willis (CoW) is an important circulatory anastomosis responsible for maintaining a stable and redundant blood supply to the brain, thereby reducing the risk of ischaemia in the event of diminished cerebral blood flow. The CoW is found at the base of the brain and surrounds the pituitary stalk and optic chiasm. The CoW is bounded anteriorly by the anterior communicating artery (ACoA) which connects both anterior cerebral arteries (ACAs). The ACAs course posterolaterally to reach the terminal segments of the internal carotid arteries (ICAs). At the point of connection between the ACA and the ICA, the lateral continuation of the ICA becomes the middle cerebral artery (MCA). The MCAs supply the lateral cerebral hemispheres excluding the superior parietal, inferior temporal, and occipital lobes, while the ACAs supply the frontal lobes in the midline and the superomedial parietal lobes. The posterior communicating arteries (PCoAs) then join the MCAs to the posterior cerebral arteries (PCAs), which form the posterior limit of the CoW. Both PCAs unite to form the basilar artery at the base of the pons, which continues caudally anterior to the pons. The PCAs supply the occipital and inferior temporal lobes.

Keywords: circle of Willis, cerebral circulation, anterior cerebral artery, posterior cerebral artery, cerebral blood supply

How to Cite?: Dr. Siddhi Doshi, Dr. Ganesh Avhad, "Anatomical Variations in Circle of Willis in Patients Undergoing Magnetic Resonance Angiography", Volume 15 Issue 1, January 2026, International Journal of Science and Research (IJSR), Pages: 1172-1181, https://www.ijsr.net/getabstract.php?paperid=SR26118121937, DOI: https://dx.doi.org/10.21275/SR26118121937