abnormal artery development abnormal basilar artery morphology abnormal basilar artery development 2017-10-11T15:14:19Z MP:0020481 aberrant formation or patterning or incomplete differentiation of the unpaired artery that is formed by the union of the two vertebral arteries, runs forward within the skull just under the pons, divides into the two posterior cerebral arteries, and supplies the pons, cerebellum, posterior part of the cerebrum, and the inner ear