THE CEREBRAL ARTERIAL CIRCLE OF A NEWBORN ASIAN ELEPHANT BRAIN (ELEPHAS MAXIMUS)

Abstract

In this anatomical study, the majority of the brain of a newborn Asian elephant was supplied with blood by the cerebral arterial circle, which lies on the ventral surface of the brain and completely encircles the optic chiasma, the tuber cinereum and the interpeduncular fossa. It was formed by the left and right internal carotid arteries and
the most rostral branches of the basilar artery. The internal carotid arteries were the incoming branches that go directly to the cerebral arterial circle, in front of the optic chiasma, and are divided into rostral cerebral arteries and caudal communicating arteries. In this study, the branches arose from the cerebral arterial circle including the
the middle cerebral arteries, the caudal cerebral arteries and the rostral cerebellar arteries, from rostral to caudal respectively. The cerebral arterial circle was formed by the anastomosing branches of the rostral and caudal communicating arteries. Five pairs forming the arterial supply of a newborn Asian elephant brain were the rostral
cerebral arteries, the middle cerebral arteries, the caudal cerebral arteries, the rostral cerebellar arteries and the caudal cerebellar arteries, respectively. The first four of these arose from the cerebral arterial circle. The fifth pair, the caudal cerebellar arteries were divided, on the right side, into two branches: the upper branch arose from
the rostral part of basilar artery and the lower branch arose from right vertebral artery. In contrast, on the left side, it was found that a single branch arose from left vertebral artery. The left vertebral artery gave off a ventral spinal artery, before joining with the right vertebral artery at the rostral level. Investigation of the basilar artery that courses rostrally showed it was gradually reduced in size and at the proximal third level, it bifurcated into small branches before receiving blood to the cerebral arterial circle. The labyrinthine artery was found with only one branch arising from the basilar artery on the right side of the brain. It lay at the mid-pons level and passed laterally between the cranial nerves VII and VIII. In Asian elephants, the cranial nerve V is supplied by the trigeminal artery, which was found with only one branch arising from the basilar artery on the left side of the brain.