abnormal hippocampus morphology abnormal hippocampal fimbria morphology abnormal fimbra hippocampus morphology any structural anomaly 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 abnormal hippocampus fimbra morphology MP:0003005 MPheno.ontology