abnormal hippocampal fimbria morphology decreased hippocampal fimbria size 2013-12-04T22:39:39Z MP:0012466 MPheno.ontology csmith reduced hippocampal fimbria reduced hippocampal fimbria size reduced size of the flattened band of efferent fibers arising from the subiculum and medial border of the hippocampus, which then thickens to form the fornix and fibers of the hippocampal commissure