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Neurology Research International
Volume 2014 (2014), Article ID 687281, 16 pages
Research Article

Anatomical Variations of the Circulus Arteriosus in Cadaveric Human Brains

Department of Anatomy, Rural Medical College, Post Loni Tal Rahata District Ahmednagar, Maharashtra 413736, India

Received 24 October 2013; Accepted 17 March 2014; Published 7 May 2014

Academic Editor: Mohammed Rachidi

Copyright © 2014 S. A. Gunnal et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Objective. Circulus arteriosus/circle of Willis (CW) is a polygonal anastomotic channel at the base of the brain which unites the internal carotid and vertebrobasilar system. It maintains the steady and constant supply to the brain. The variations of CW are seen often. The Aim of the present work is to find out the percentage of normal pattern of CW, and the frequency of variations of the CW and to study the morphological and morphometric aspects of all components of CW. Methods. Circulus arteriosus of 150 formalin preserved brains were dissected. Dimensions of all the components forming circles were measured. Variations of all the segments were noted and well photographed. The variations such as aplasia, hypoplasia, duplication, fenestrations, and difference in dimensions with opposite segments were noted. The data collected in the study was analyzed. Results. Twenty-one different types of CW were found in the present study. Normal and complete CW was found in 60%. CW with gross morphological variations was seen in 40%. Maximum variations were seen in the PCoA followed by the ACoA in 50% and 40%, respectively. Conclusion. As it confirms high percentage of variations, all surgical interventions should be preceded by angiography. Awareness of these anatomical variations is important in neurovascular procedures.