abnormal hippocampal fimbria morphology increased hippocampal fimbria size greater 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 enlarged hippocampal fimbria 2013-12-04T22:39:39Z csmith MPheno.ontology MP:0012465