A neuroanatomist called Rexed looked at the structure of the grey matter of the spinal cord and divided it into columns of cells that were similar to each other in different segments.
His observations were based on the shape and size of the neurones, and he divided the grey matter into 10 (Roman X) layers and 6 of these are in the dorsal horn, numbered I to VI .
The classification has been useful in that the different lamina have neurones with different functions.
Neurones involved in Sensation
Lamina I was the marginal layer or zone.
Lamina II had a gelatinous appearance and is sometimes called the substantia gelatinosa.
Lamina IV and V
had larger cells and this area has also been called the Nucleus Proprius
In Lamina VI another anatomist gave his name to Clarke's column, sometimes called the nucleus dorsalis.
Lamina X is the area around the central canal