Nucleus proprius of spinal cord

The nucleus proprius is a layer of the spinal cord adjacent to the substantia gelatinosa. The nucleus proprius can be found in the gray matter in all levels of the spinal cord. It constitutes the first synapse of the posterior gray column carrying proprioception, two-point discrimination, and vibration sensations from peripheral nerves. Cells in this nucleus project to deeper laminae of the spinal cord, to the posterior column nuclei, and to other supraspinal relay centers including the midbrain, thalamus, and hypothalamus. Rexed laminae III and IV make up the nucleus proprius.

On the other hand, the substantia gelatinosa of Rolando (Rexed lamina 2) are involved in sensing pain and temperature.