Horns of Ammon

Cornu Ammonis

CA region

Cornu Ammonis forms the larger part of the seahorse, the hippocampus, and consists of archaic 3-layered cerebral cortex (allocortex/archicortex) where the nerve cells, large pyramidal cells, are arranged in a compact layer that, in a cross section through the hippocampus, forms an S-shaped figure, Cornu Ammonis (CA region) reminiscent of the Egyptian god Ammon's horn; the god Ammon had the head of a ram/ram. The inner, medial, edge of the Cornu Ammonis is enclosed U-shaped by the dentate ring (gyrus dentatus) also lined with the allocortex.

In a cross section through the hippocampus, the CA region is divided into 4 sections: CA1, CA2, CA3 and CA4.