CoursesHistologyBody systemsNervous systemHippocampal region

Hippocampal region

Learning objectives

After completing this study unit you will be able to:

Explain the structure and function of the hippocampus.
Name the layers of the cornu ammonis and the dentate gyrus.

Browse atlas

The hippocampus is part of the limbic system and plays a crucial role in memory and spatial information formation as well as retrieval. It is located in the medial temporal lobe and is characterized by its unique twisting structure that resembles a seahorse, hence its name. The hippocampal region is composed of three parts: the hippocampus (also known as hippocampus proper or Ammon’s horn), the dentate gyrus and the subiculum.

Based on histological critera, the hippocampus is part of the archicortex. It has four layers in the cornu ammonis (CA) and three layers in the dentate gyrus. The four layers of the hippocampus proper are divided from superficial to deep into CA1, CA2, CA3 and CA4. The three layers of the dentate gyrus are the molecular layer, the intermediate granular layer and the multiform layer.

Afferent fibers reach the dentate gyrus via the lateral and medial perforant pathways, whereupon the information is further processed in the cornu ammonis. Efferent fibers then run as axons of the pyramidal cells via the subiculum to the fornix before the information is passed on to other structures such as the mammillary bodies, the hypothalamus, the amygdaloid body and the septal nuclei.