Circulus arteriosus cerebri: a study of variation in the fetal and adult human brains of south Indians.

The Circle of Willis or Circulus Arteriosus Cerebri and its branches are subject to many variations. The Circle of Willis with a classical description is very rare. The constituent arteries forming the circle vary greatly in size in different individuals and on two sides in the same subject. Study by dissection or by angiographic methods by several workers has shown that deviations from the normal pattern occur in a very high proportion of cases. There are differing views regarding the variations in the circle. Thus, this study was done to compare our findings with the others. In the present study, each artery taking part in the circle has been described in relation to the length, size and its origin separately and the findings have been compared.