The hippocampus is a C-shaped structure of the human brain. It is located deep within the temporal lobe, being part of the lower and medial wall of the cerebral hemisphere. It forms a ridge on the floor of inferior horn of each lateral ventricle. Together with the amygdala and hypothalamus, it is part of the limbic system, which is involved in emotional reaction, long-term memory, and autonomic functions.
Topography and Structure
The hippocampus consists of a relatively simple three-layered cortex throughout its extent. It is connected to the mammillary body through the fornix, which is composed of nerve fibers. The hippocampus can clearly be differentiated into three longitudinal parts: 1) the subiculum, which is the most anterior portion; 2) Ammon´s horn, which is the middle and thickest portion of the hippocampus body; 3) dentate gyrus, which is the medial strip situated above the hippocampal fissure. The dentate gyrus, so called because of its toothed surface, is morphologically the most medial part of the cerebral cortex.
The cortex of hippocampus consists of three layers: 1) an external molecular layer; 2) a middle granular layer composed of granule cells (a type of neuron), and 3) an internal polymorphic layer. In the molecular layer, the axons of the granule cells gets into synaptic contact with afferent nerve cells of the entorhinal cortex.
Below, a picture of a portion of temporal lobe containing the hippocampus, which lies on the floor of the lateral ventricle.
