Variations of the anterior part of circle of Willis in human cadavers: a dissection study

Abstract

Background: Vascular anatomy of anterior cerebral artery (ACA), anterior communicating artery (ACoA) and its branches is quite complex and known for its variations. Most of the variations have been reported on posterior cerebral and posterior communicating arteries. However, there are very few case reports regarding variations encountered in the ACA and ACoA. Hence, the present study was undertaken to study the origin, course and termination of ACA, to observe the ACoA, and to observe variations associated with them . Methods: 30 human brain specimens were removed from embalmed cadavers. Vernier calliper was used to measure the length and external diameter of ACA and ACoA. Variations were observed with reference to presence or absence, size, shape and mode of anastomosis. Results: Out of 30 cases; in anterior part, the circle of Willis was incomplete in 1 case and anomalous in 5 cases. Pre-communicating ACA (A1 segment) was absent in 2 cases and hypoplastic in 1 case. Azygous ACA was seen in 3 cases. ACoA was absent in 4 cases. Out of the 26 cases of ACoA, ‘H’ shaped ACoA – ACA complex was most commonly found. Conclusions: Variations of the anterior part of circle of Willis are not quite rare as believed.