In the gray matter of the spinal cord can be found a large numbers of neurons. These neurons are of different types and are grouped into different areas.
To understand this structure have been proposed different forms of classification, which are shown in this interactive image.
The simplest classification divides the gray matter in three basic areas or "horns": dorsal, lateral and ventral.
In a classification that caters exclusively to morphological criteria, the gray matter is divided into different "nuclei".
In another classification which serves both morphological criteria and functional criteria (connectivity), gray matter is classified in areas that are called Rexed laminae.