Abstract
Introduction:-The embryologic development of intracranial circulation is truly one of Nature’s marvels. Recognition of anatomic variants is increasingly important for various neurosurgical procedures. Posterior part of circle is formed by the posterior cerebral arteries (PCA), terminal branch of basilar artery (BA), connected to internal carotid arteries (ICA) by the posterior communicating arteries (PComA). Variations of posterior cerebral and posterior communicating arteries are not uncommon. Material & method – We were studied 60 adult fixed human brains during the period of six years in dissection hall of Muzaffarnagar Medical College, Muzaffarnagar for variations in the posterior part of cerebral arterial circle. In eight cases (four right and four left),I.e. in 11.3 % cases, we observed hypoplasia of P1 segment of posterior cerebral with a dominant posterior communicating artery continuing as posterior cerebral artery and supplying occipital lobe.This configuration referred to as “fetal type of posterior communicating artery.This was also found in 28% cases (Avci & Baskaya, 2003). In such cases the internal carotid artery provides major supply to the occipital lobe. This variant was found in 10 % cases unilaterally and 5 % cases bilaterally. (Caldemayer et al. 1988; Van Overbeeke et al 1991). These variations in the posterior part of cerebral arterial circle are relevant to vertebro-basilar ischemia and infarcts in the territory of posterior cerebral artery.

Key words: Posterior cerebral artery, fetal type of posterior communicating artery, vertebra-basilar ischemia.