Hippocampus, the half horse/half fish sea creature of Greek mythology that pulled Poseidon's chariot; from hippo, horse and kampos, monster.

The Hippocampus. Graphic published in European Neurology 2005;53:171-178

Anatomically the hippocampus is a limbic system structure deep in temporal lobe of the cerebrum; it is crucial for the processing of long-term memory. The sinuous arrangement of its gray and white matter, when seen in a frontal section, is suggestive of the curves of the Hippocampus's tail, inspiring Giulio Cesare Aranzio, an eminent Italian anatomist of the 16th century, to give it the name.

The hippocampus is one of the first structures to show degenerative changes in Alzheimer's disease.

Hippocampus is also the genus name of the fish known as the seahorse.

Hippocampus in a frontal section: the dentate gyrus is the head, the subiculum is the tail. Click here for a larger view From Frank Gaillard Designs