103 Bratisl Lek Listy 2006; 107 (4): 103106 TOPICAL REVIEW History, anatomical nomenclature, comparative anatomy and functions of the hippocampal formation El Falougy H, Benuska J Institute of Anatomy, Faculty of Medicine, Comenius University, Bratislava, Slovakia Address for correspondence: H. El Falougy, MD, Inst. of Anatomy, Faculty of Medicine, Comenius University, Spitalska 24, SK-813 72 Bratislava 1, Slovakia. Phone: +421.2.59357374 Institute of Anatomy, Faculty of Medicine, Comenius University, Bratislava, Slovakia.hisham.elfaloughy@fmed.uniba.sk Abstract The complex structures in the cerebral hemispheres is included under one term, the limbic system. Our conception of this system and its special functions rises from the comparative neuroanatomical and neurophysiological studies. The components of the limbic system are the hippocampus, gyrus parahippocampalis, gyrus dentatus, gyrus cinguli, corpus amygdaloideum, nuclei anteriores thalami, hypothalamus and gyrus paraterminalis Because of its unique macroscopic and microscopic structure, the hippocampus is a conspicuous part of the limbic system. During phylogenetic development, the hippocampus developed from a simple cortical plate in amphibians into complex three-dimensional convoluted structure in mammals. In the last few decades, structures of the limbic system were extensively studied. Attention was directed to the physi- ological functions and pathological changes of the hippocampus. Experimental studies proved that the hippocampus has a very important role in the process of learning and memory. Another important functions of the hippocampus as a part of the limbic system is its role in regulation of sexual and emotional behaviour. The term hippocampal formation is defined as the complex of six structures: gyrus dentatus, hippocampus proprius, subiculum proprium, presubiculum, parasubiculum and area entorhinalis In this work we attempt to present a brief review of knowledge about the hippocampus from the point of view of history, anatomical nomenclature, comparative anatomy and functions (Tab. 1, Fig. 2, Ref. 33). Key words: hippocampal formation, history of medicine, nomenclature, comparative anatomy, function. Hippocampus in the history of medicine The history of medicine is rich in pioneers, who lighted the way of the modern science. In this part we present the role of some of them in studying the hippocampus. Arantius (1587) described in his book De Humano Foetu the structure in the temporal horn of the lateral ventricles that looks like hippocampus (sea horse) or bombycinus vermis candidus (white silkworm), (Sano, 1997). In literature only the first term gained popularity and is in use till today. This term is extracted from the Greek hippokampos: hippos, horse; +kampos, sea monster (Pearce, 2001). According Walther (2002) the careful reading of the entire original text of Arantius leads to the conclusion that it was not the hippocampus in our modern terms but the dentate gyrus, which he compared to a little sea horse or a silkworm. Diemerbroeck in 1672 added a foot to each seahorse and called it pes hippocampi. In the 18th century, Vicq dAzyr dis- tinguished the hippocampus major and minor. He defined the hippocampus minor as an eminence in the floor of the occipital horn of the lateral ventricle, calcar avis in the modern nomencla- ture (Bentivoglio and Swanson, 2001). The coronal section of the hippocampus reminded Winslow (1732) of the shape of the rams horn, because of that he named it cornu arietis. De Garengeot (1742) chose more mystical term, cornu Ammonis (Sano 1997). Ammon, the hidden, is the chief god of Theba in ancient Egypt. It was presented as a ram headed man, or a ram headed sphinx. Tarin (1750) differentiated structure, which he called fascia dentate, from the rest of the hippocampus. Huxley (1861) pro-