The grey matter of the spinal cord is divided into a number of nuclei. These are also functional divisions and the cell sizes in these various nuclei reflect their functions.

The nuclei of the dorsal horn are related to the incoming sensory fibers. The motor neurons, located in the ventral horn, are generally larger than the sensory neurons. The grey matter inbetween is often called the intermediate grey and has a spectrum of cells.

In the centre of the cord is the remnant of the neural tube the central canal, surrounded by some grey matter.

The names of the nuclei of the spinal cord are somewhat long and sometimes obscure (and difficult to spell).

There has been a second way of categorizing these nuclei, in lamina, using a numbering system. The equivalent names and numbers are given below: